One ton axle swap- 83 K10

[SFDfirefighter]

Hi guys,

I just recently bought an 83 K10. It has a stock 305 with I believe a TH2004R transmission, NP205 transfer case, and a 10 bolt front and rear axle. I am currently building a 350 with a TH350 transmission which I plan to drop in place of the 305 until I can build my 450 horse 383. My plans are to put a 12" Superlift with 40" Toyo Mt's. I know that the 10 bolts will not hold up with the amount of tire I'm planning to put, and not to mention the amount of torque I plan for the 383 to have.

My question is which Dana 60 and 14 bolt should I try to find to swap the 10 bolts? If I can find a set from a 73-87, will it be a direct bolt up or am I going to have to modify them somehow? Also what gears should I plan on putting in them as well?

Any help is greatly appreciated! Also any input from someone that has done this lift will also help.

Thank-you, Ryan.

 

[Driver4r]

Run a set of 5:13's

 

[HotRodPC]

It's not a 200-4R unless the Tcase is divorced. And it's an over driver trans? Hmmm, Unless there is a way to fun the 200r4 that I'm unaware of, but fairly certain the Th200-4R is a fixed tailshaft housing and noway to put a Tcase adapter on it. I'm gonna throw a guess out there and say it's a 3 speed auto and a Th400/Np205 which is not OEM for a K10 at all.
With that Tire size, yeah 5.13's minumum. It you are running a Th400 and that much torque, you can get by with 4.56's or 4.88's and hold up well. With what you got in mind, if that's a Th400/NP205 combo, I'd hold what you got with that, and just do the motor swap and axle swap.

 

[crazy4offroad]

80-87 kingpin D60 is what you should be looking for. For the 14 bolt get a 3/4 ton so you dont have to worry about the axle width, spring perch spacing, etc it will bolt right in and be the same full-floating 10.5" ring gear 550 pound heavy ass bastard as the 1-ton unit lol. You should try to avoid the 84 model I think it is, it has a smaller pinion support bearing and could throw off your build. Most setup kits however come with the bigger bearing incase you accidentally end up with one.

You'll probably also want to convert the rear to disk brakes and lighten it by as much as 150 pounds by ditching those heavy drums. However your park brake options evaporate, you can either use the old Cadillac El Dorado calipers that are hard to keep adjusted, or check out the vender here on the forum R1 Concepts and see what they offer. I know of another source but they are very expensive and may not be anything better than the caddy calipers. Since mine is tagged Antique I dont have to worry about inspection and just never tried to get a park brake, although I wish I had one at times. A line-loc may be an alternative.

For the lift you may want to call Offroad Design and check out their crossover/highlift steering kits. You'll need a 2WD steering box for left/right pull of the drag link instead of the front/back pull of the K10 box. Here's some links you'll want to bookmark:
http://www.pirate4x4.com/tech/billavista/14b_bible/index.html
http://www.pirate4x4.com/tech/billavista/60_front/
http://offroaddesign.com/catalog/Dana60crossover.htm

Also noteworthy is the use of the F*rd high-pinion D60 front. The pinion is above the centerline of the axle so your front driveline angle is better. There's another user here who has done this swap, Sean1960, you may want to check out his albums...
http://www.gmsquarebody.com/forum/member.php?u=760
You would need a driver drop t-case, probably a F*rd NP205 would be an excellent choice.

 

[HotRodPC]

Hey, While we're on this subject and I don't have to hijack a thread, I can simply step in, on a CUCV that is rated 1.25 ton, the 14 bolt Full Floater rear end that comes OEM with 4.56 gears and the Detroit Locker, isn't that perch spacing the same as a 3/4 ton and the shock mounts too??? Basic simple swap with 3/4 ton squarebodies isn't it?

 

[crazy4offroad]

Not sure about that but the easy answer I can give you is 42.5" center pin to center pin on the leaf spring perch = easy swap into 1/2 and 3/4 tons.

 

[SFDfirefighter]

Thanks for the replie guys. I'm not exactly sure what transmission it is, I've only crawled under there once, guess I'll have to get under there again. Also I found a 3/4 ton axle for 200 bucks, but it's out of a newer 90's model. Will this still work or do I need to stick with the older model 14 bolt? Thank y'all again for the replies! As soon as I can go out and look at the trans again I'll post it.

 

[crazy4offroad]

That 3/4 ton is the same as the 10-bolt front you got now except with 8-lug outers and a little bigger brakes. Get some pics while youre under there maybe we can help identify the trans.

 

[SFDfirefighter]

Thanks I'll do that. Also I didn't specify on my last reply, it's a 14 bolt rear end out of a 97 3/4 ton. After reading up online, maybe it is a 208 t-case instead of the 205? As soon as I can get it on the lift again I'll take pictures of both and put them on here. Thanks again for your help, much appreciated.

 

[HotRodPC]

And NO, that 90's axle will not just bolt right. Perches are different. Also the 4x4 is wider than the 2wd in the 90's models body style. Everything that is 1/2 and 3/4 ton in this Squarebody body style will fit in it. So if it's in a K5 Blazer or Burb up to 91, then yes it would fit. Kinda learning this myself cuz I wanted to convert one of my 14b Seml Floats to 6 lug as a 1/2 ton upgrade.
And do get a pic of the trans. I have a feeling its a Th400 if you think it's a 200-4R cuz of the wierd shape. For your intentions, I'd keep it that way too, but do get us some pics.

 

[SFDfirefighter]

Well when I got under there I thought it was a 400 as well, but the bolt count seemed different. I read that the 400's were changed out with a 700R4, but again I only put it on the lift once and didn't pay too close attention. Also it's not too weird of a shape, but again the bolt count messed me up (maybe I need to go back to school and learn to count). Also your last post brings me to a new question. Full float or semi float rear? Thank y'all again for all the information, I've learned a lot of stuff from y'all already.

 

[HotRodPC]

Thanks I'll do that. Also I didn't specify on my last reply, it's a 14 bolt rear end out of a 97 3/4 ton. After reading up online, maybe it is a 208 t-case instead of the 205? As soon as I can get it on the lift again I'll take pictures of both and put them on here. Thanks again for your help, much appreciated.

So then someone had to have removed and rewelded the perches. If it's 6 bolt, from a 4x4 model, so that its the same width as a square body then I'd rock it until you get your Dana 60 then you'd have to upgrade to 8 lug wheels. And when you get ready do that, lemme know. I'd glady swap you out for a 85 3/4 ton 14b Semi Float with 4.10 ratio and 8 lugs ready to bolt right into your truck right now. Of course if you're going with D60 up front ,you probably want a 14b Full Float. I won't give up my 4.56 Detroit Locker CUCV Full Floater for that, but I acquire another 14b FF, I'll sure let you know.

 

[SFDfirefighter]

Sorry hotrodpc, the 3/4 ton axle I was talking about is one that I was hoping to buy and put under my truck. Mine right now has a 10 bolt front and rear.

 

[HotRodPC]

Well when I got under there I thought it was a 400 as well, but the bolt count seemed different. I read that the 400's were changed out with a 700R4, but again I only put it on the lift once and didn't pay too close attention. Also it's not too weird of a shape, but again the bolt count messed me up (maybe I need to go back to school and learn to count). Also your last post brings me to a new question. Full float or semi float rear? Thank y'all again for all the information, I've learned a lot of stuff from y'all already.

If it's the original trans aka OEM, then it's a 700r4/NP208 Tcase. Easy to tell on the Tcase. If it's aluminum and not cast iron, it's the 208. Don't worry about bol count on the trans. Go by the shape of the pan. If its rectangle it's 700r4. If it's square with a corner cut off, it's a Th350.If it's a long rectangular shape with some corners cut off and some low and high sides in the pan it's a 200-4R but I say not likeley at all. If it's got a wierd shape hard to describle it's a Th400.

If yours is a 14 bolt and 6 lug out of a 97, then it's for sure a Semi Float. Full Float is not available in 6 lug at all unless someone spent an assload of cash for conversion and I say they didn't do that. They went with the 97 14b SF as a half ton upgrade rear axle.

 

[SFDfirefighter]

I believe it's a stock rear end, but I'm not worried about it anymore anyways since it won't be a direct bolt on. When I look for a rear end, would a full float be better than a semi float?