K10 suspension upgrades?

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iamtherealJayy

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Alright I think it’s time to upgrade the work truck lol, I’ve got a 1978 Chevrolet K10 Bonanza that’s been my work truck for several months now. The truck runs fine drives ish fine and has a utility bed so it’s great for what I do. Although I’m thinking about upgrading from half ton suspension to atleast 3/4ton if not full on dually swap the rear end and get a dually utility bed ( deeper boxes heck yea) but out of all the reading I’ve done this morning I’m thinking the 3/4 ton would be easier? I’ve read about the one ton rear ends having spring hangers in different locations? This isn’t a pulling truck by any means so I’m not worried so much about damaging the frame or anything. The truck is very well loaded with tools and occasional material in the bed but that’s all I’m never going to pull massive loads with this rig. I debated on buying a K30 and just moving all my stuff to it and returning this truck to a normal pickup bed, but there’s no decent k30’s near me for under 5 figures. I do have the lead on a k20 I’m stealing the frame out from under for my 87. I’ll have the axles from that truck so I could make it 3/4 ton for time being? But my overall question is, is it really worth it? Or should I just get some helper springs and a small lift for the front? The truck is on small tires currently but there’s not much room from the tires and the bed and the receiver in the back almost drags the ground if I’m on uneven ground. My overall plan would be perfect scenario get the frame from the parts k20 for my 87, take the suspension currently on my 87(2.5 lift) and put on this truck and get a bigger lift for the 87. Make sense? I didn’t think so but, lol. I’m mainly wanting the dually rear end for the dually utility bed and 3/4ton+ springs so I don’t feel bad for the half ton suspension. Here’s some photos I’ve got of the truck so maybe you can come up with opinions.
 

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iamtherealJayy

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I’m fine with just using 3/4 ton axles and better springs, better springs is what I’m after and I wanted the dually rearend to get a dually utility bed for more room. I’d run half ton gear all day but my opinion it would look a little funky having a big utility bed for a dually on a single rear wheel and a half ton at that lol. This truck isn’t being built for pulling anything that I wouldn’t already use a half ton for. I’ve got bigger trucks for bigger tasks this truck is solely for hauling around my tools and occasional materials.
Edit: I’m already getting a parts truck that’s a k20, so I’m willing to swap in 3/4ton axles and I’ve already got dually wheels I can run in the rear. I’m 100% fine running a standard front wheel over a dually wheel but what goes into putting duals on a srw axle? Longer studs? A spacer? I’m fine with running a small spacer if need be ive had 1.5” spacers on this truck previously. I had plans of originally making this truck just a regular pickup bed and giving it to my sister as her first truck and buying a true k30 as a new work truck but plans changed and she got her hands on a 1980 C30 crew cab(lucky) so she doesn’t want my clunker anymore. My plans are to build this to be a reliable work truck since everything (in my opinion) is easier than just getting a newer vehicle to serve me.
 
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AuroraGirl

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I’m fine with just using 3/4 ton axles and better springs, better springs is what I’m after and I wanted the dually rearend to get a dually utility bed for more room. I’d run half ton gear all day but my opinion it would look a little funky having a big utility bed for a dually on a single rear wheel and a half ton at that lol. This truck isn’t being built for pulling anything that I wouldn’t already use a half ton for. I’ve got bigger trucks for bigger tasks this truck is solely for hauling around my tools and occasional materials.
Edit: I’m already getting a parts truck that’s a k20, so I’m willing to swap in 3/4ton axles and I’ve already got dually wheels I can run in the rear. I’m 100% fine running a standard front wheel over a dually wheel but what goes into putting duals on a srw axle? Longer studs? A spacer? I’m fine with running a small spacer if need be ive had 1.5” spacers on this truck previously. I had plans of originally making this truck just a regular pickup bed and giving it to my sister as her first truck and buying a true k30 as a new work truck but plans changed and she got her hands on a 1980 C30 crew cab(lucky) so she doesn’t want my clunker anymore. My plans are to build this to be a reliable work truck since everything (in my opinion) is easier than just getting a newer vehicle to serve me.
a waste of time, gas, effort, tire,
If you want to have the tires moved out, get a wider axle, space out. or.. something... I dont see the need.
get a tool bed thats for a half ton truck not a 3/4 ton truck. about all I can say lol...

Get really wide rear tires and wheels maybe?
 

iamtherealJayy

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The bed fits fine currently, I was just hoping to upgrade. I wanted to go with 3/4 ton suspension since it’s a work truck and carried a bit of weight. And the dually was so I could get a bigger bed
 

Grit dog

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If you’ve got matching 3/4 ton F and R axles on the way, that seems like the obvious choice both budget and availability wise. Especially if you got springs to go with it.
Only downside is you’ll lose the sweet brodozer wheels!
 

iamtherealJayy

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I agree lol it was kinda cool finding those wheels. Found a sweet deal on them snagged them for $400 off of a early 60’s c10 tires are old but brand new. Will the 3/4 ton stuff bolt right in?
Edit: odd topic question, does anyone else have the mirrors like this truck has? My passenger side mirror is about useless it’s so low the door blocks majority of it. I was wondering if there’s any adjusting I can do to it to bring it up some maybe? I’d understand it being low if I was a shorter person lol
 

Grit dog

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Dimensionally, I believe they're the same. Front axles are actually the same, with different hubs, 6 or 8 lug.
You have a K20 sitting next to your K10, why not measure?
 

iamtherealJayy

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You know, you’ve got a point, I’ve got 2 k10’s and an 87 V20. I’ve got everything except a c20 and a k30 on the property. What exactly do I need to measure? Spring hanger to spring hanger? Width of spring perches? Will I have to change my brake lines? I know the brakes will be larger. Will my parking brake hook right up? I’m not sure what all goes into changing an axle I honestly try to avoid axles.
 

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You will have to change the master cylinder to 3/4 ton. Brake lines, parking brakes, and valve are the same. I think the calipers are the same but not 100%. The only thing I would worry about is the frame if you're going to start hauling a load. I have managed to break every 1/2 ton frame I've had. Check the frame around the steering box and just behind the rear cab mounts, and the engine crossmember at the passenger's side motor mount for cracks. Other than that it's pretty straight forward. Rear drive shaft needs the larger joint. As for the towing mirrors, they are just a pain. I took mine off and went with the more modern GM mirror
 

iamtherealJayy

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I don’t plan on hauling much maybe pulling an occasional small load. Nothing a half ton isn’t capable of. If I’ve got the parts truck could I just use the 3/4ton driveshaft? Would that fit right in the np205 tcase?
 

Juggernaut

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Depends on what joint is on there now. I had to use a conversion joint for a while, but that was on my old NP 203 case. Check the diameter of the cap. Also, make sure the drive shaft is the correct length. Measure yoke to yoke in the same place on both trucks and see if it matches.
 

iamtherealJayy

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Well I bought an early 80’s one ton today, it’s show time. Plan on using the frame for my 87. I thought it was a 3/4 ton at time of purchase but turns out to be a 1 ton. I need to determine axles and figure out what I want to use. I wanted to use my existing axles in my 87 with this frame but if I’ve got a FF rearend and a d60 front end I might as well keep those and use the 87 axles for my k10. Is there any obvious things to tell what axles I have? Rpo code? Anything. I just happened to notice the abnormally large rear pumpkin and that’s what got me thinking it’s a one ton.
 

AuroraGirl

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Well I bought an early 80’s one ton today, it’s show time. Plan on using the frame for my 87. I thought it was a 3/4 ton at time of purchase but turns out to be a 1 ton. I need to determine axles and figure out what I want to use. I wanted to use my existing axles in my 87 with this frame but if I’ve got a FF rearend and a d60 front end I might as well keep those and use the 87 axles for my k10. Is there any obvious things to tell what axles I have? Rpo code? Anything. I just happened to notice the abnormally large rear pumpkin and that’s what got me thinking it’s a one ton.
you should do a few things

1) pics
2) Tag on the axle, pic of RPO sheet, or otherwise visually show us what you got (pics #2 I guess)
3) your rear axle is most definitely different, on a 1 ton. especially if its a dually application. your front is good like you said. what trans?
Its probably a D70 or whatever the non 14 bolt rear was
 

iamtherealJayy

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The RPO codes say heavy duty spring front and rear but also says 305 cuin for engine option lol. I’ll get pics it’s dark now. I already got the truck running it’s currently got a 350 good wrench engine in it and a manual trans and np205 tcase. The front hubs are very different from what I’m used to. It’s got the locker bolted to something bolted to the rotor. I haven’t taken a wheel off yet to verify full floater rear end but it’s got a huge pumpkin and huge brake drums. I’ll possibly be making another thread dedicated to fixing this truck because I’m gonna run it for a while before tearing it apart to make my other trucks how I want them.
Edit: the rear end is a 14 bolt if I could count correctly.
 
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AuroraGirl

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The RPO codes say heavy duty spring front and rear but also says 305 cuin for engine option lol. I’ll get pics it’s dark now. I already got the truck running it’s currently got a 350 good wrench engine in it and a manual trans and np205 tcase. The front hubs are very different from what I’m used to. It’s got the locker bolted to something bolted to the rotor. I haven’t taken a wheel off yet to verify full floater rear end but it’s got a huge pumpkin and huge brake drums. I’ll possibly be making another thread dedicated to fixing this truck because I’m gonna run it for a while before tearing it apart to make my other trucks how I want them.
Edit: the rear end is a 14 bolt if I could count correctly.
what is the ratio? 14 bolts came in 4.10 and 4.56 but the danas came in a slightly different ratio

to confirm full floater you shouldnt have to take your wheel off. can you unbolt the center and yank a shaft out?
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heres a 14 bolt, from a 3/4 ton tho, just for a showing of what it looks like
 

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