Correct Driveshaft Length for 700-R4/NP208/14bolt FF

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bucket

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Squarebody 14ff axles used a 1350 joint, even the 1-tons.
 

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so did ya still want a measure i can use my foot again
 

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so did ya still want a measure i can use my foot again
Thanks for offering, but I decided to order one of the M1008 driveshafts from ebay. I really dislike ebay, but getting a NOS drivesahft with good U-joints delivered to my door for under $200 seems like the best option I've found thus far.
 

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That shouldn't be the case. The only inside U-joint universals I have ever seen on a squarebody are the double cardan universals. All chevrolet rear driveshafts I have ever seen use outside snap rings. A 14BFF should be a 1410 yoke. My stock K25 rear driveshaft that was a slipyoke into a NP205 and with a 14BFF had 1410's on both the axle yolk and the slip joint yoke side.

Just for the record, this is my spare '85 K10 driveshaft. It uses the inside snap ring U joints to mate with the GM 10 bolt. I thought all 8.5" 10 bolt rear ends used this style of U joint??? My K10, Camaro, and Monte Carlo all do.

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Squarebody 14ff axles used a 1350 joint, even the 1-tons.
ooops, I had to go check again. Sure enough.. they were 1350's I got to rebuild my rear driveshaft(ACdelco 45u0103). The front 10 bolt took a 1330 at the yolk(45u0107) and two 3R internal snap ring universals for the double cardan(AC Delco 45u0108).

Just for the record, this is my spare '85 K10 driveshaft. It uses the inside snap ring U joints to mate with the GM 10 bolt. I thought all 8.5" 10 bolt rear ends used this style of U joint??? My K10, Camaro, and Monte Carlo all do.

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I'm having a hard time with this picture. I'm sure I'm just looking at it wrong. Does this have the snap rings installed on all 4 caps in the picture? Is that why I'm seeing that ridge?
 

scrap--metal

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I'm having a hard time with this picture. I'm sure I'm just looking at it wrong. Does this have the snap rings installed on all 4 caps in the picture? Is that why I'm seeing that ridge?

Yes, the snap rings are on all 4 caps and that's the ridge your seeing. The cap oriented in the 6 o' clock position shows the end of one of the snap rings.

I didn't take measurements against bucket's chart from post #40, but I'm pretty sure they're the 3R style.
 

scrap--metal

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The M1008 driveshaft showed up yesterday. It's about the same length as my spare K10 driveshaft, maybe an 1/8 longer, but much heavier/stronger. After seeing them side by side, I'm glad I didn't cheap out with the conversion U-joint option. I think M1008 driveshaft is also larger in diameter than the short K20 driveshaft that was in my truck. I didn't take measurements to confirm that.

After getting it in the truck, I took it for a drive. I don't know how fast I was going since my speedometer cable is too short to reach my transfer case, but my driveshaft vibration was gone. I still have old flat spotted tires, so that's another issue, but I believe the driveshaft vibration has been fixed.

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Thanks everyone for your help with this.
 

AuroraGirl

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how much is the difference side to side? Like when you put it on, because I am curious to see the size difference.
 

scrap--metal

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how much is the difference side to side? Like when you put it on, because I am curious to see the size difference.

I'm confused by your question... How much is what difference? Please clarify and I'll be happy to answer.

And I love your BFG's! Those look like the original TA KOs... not the KO2's. They haven't made the original BFG TA KO's in a number of years, but yours still appear to be in good shape.
 

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I'm confused by your question... How much is what difference? Please clarify and I'll be happy to answer.

And I love your BFG's! Those look like the original TA KOs... not the KO2's. They haven't made the original BFG TA KO's in a number of years, but yours still appear to be in good shape.
Two things 1) pictures can often be deceptive and those sides were face down for a few years while they sat in the sun(2 I think) they were replaced when the one set was work enough it was “time” but they were the match to the back set Which had maybe 5-10k lucky left, but my step dad wanted new shoes for winter. Even tho not much tread on front they were way better than bald bias ply. Lol. Anyway… the insides look nice sure. But you haven’t seen the one I took off and put the spare on in its place. It leaks air. But it’s from the entire circumference in a circle about half way between the center and outer edge of the tire where the broken belt I think we all came to think.
Also a bulge but I wouldn’t be worried about that as much as the belt. Because the weight of the front of the truck is A LOT with nothing in it tbh and it’s handled that because the spring set. But the plow is dangerously too heavy to put a tire with both a bulge and belt that smashes into snow and pivots on the weight of the truck, jerky 4wd etc. So since I haven’t gotten to the rear brakes or the front driveshaft u joints I figured I’d put the taller spare on the truck unlock the hubs and put a note in plain English on the tire with my cool wax marker SPARE and a mean sticky note in the cab on the shifter. So I don’t try and use 4wd and blow up my np208.

Anyway, I meant like the diameter and the length. Like is it just longer or is it larger? My shaft just seems larger but it could be photos or compensation attempts so I wanted to see. I have no for sure that mine is from a 85-86 truck but I assume because the slip and 14 bolt fit.
 

scrap--metal

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^Well then it might be time for new BFG's... I was surprised how good the set of 15 to 20 year old tires still looked.

The M1008 driveshaft is definitely longer then the driveshaft I pulled from my K20. M1008 is 54 3/8" from U-joint center to center. I measured my K20 driveshaft to be 52 3/4" long.

I will try to take diameter measurements on the driveshafts in the next day or two. I already stuck the K20 driveshaft up in the garage attic, so I'll have to make a little time for it.
 

AuroraGirl

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^Well then it might be time for new BFG's... I was surprised how good the set of 15 to 20 year old tires still looked.

The M1008 driveshaft is definitely longer then the driveshaft I pulled from my K20. M1008 is 54 3/8" from U-joint center to center. I measured my K20 driveshaft to be 52 3/4" long.

I will try to take diameter measurements on the driveshafts in the next day or two. I already stuck the K20 driveshaft up in the garage attic, so I'll have to make a little time for it.
the date code on the tires is 2016 LOL
 

AuroraGirl

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^Well then it might be time for new BFG's... I was surprised how good the set of 15 to 20 year old tires still looked.

The M1008 driveshaft is definitely longer then the driveshaft I pulled from my K20. M1008 is 54 3/8" from U-joint center to center. I measured my K20 driveshaft to be 52 3/4" long.

I will try to take diameter measurements on the driveshafts in the next day or two. I already stuck the K20 driveshaft up in the garage attic, so I'll have to make a little time for it.
have any pic side by sides or just the one on your truck? I just want to see and check something I also got lol
 

AuroraGirl

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Engine Size
400(?), 350
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for tire pic lol
 

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