Burban c20 14 bolt ff to k10 ?

[BigBlackChevy77]

Hey guys so I saw a previous post on here about someone picking up a c20 axle from a late 70s pickup and wanting to swap it on a k10. I'm in a slightly different situation. I got a 14 bolt ff for another truck but can't use it so it has been taking up space. It is from a mid to late 70s c20 suburban. I'm assuming it would not be an easy task to get that to bolt up to my 1977 k10 with a 12 bolt rear ? I have a np205 and sm465 if that helps.

 

[Charlie]

 

[BigBlackChevy77]

Thank you !

 

[Craig 85]

I've done a couple of 1/2 ton to 3/4 ton axle swaps. The last one I did was on a '79 K15. My truck was already lifted when I purchased it, so when I install the 14 bolt, I had to have the driveshaft shortened since the pumpkin is larger than a 12 bolt. You will need U-bolts for a 3/4 ton axle and the spring plates as the 3/4 ton has larger diameter tubes. I think I also had to shorten my parking brake cable too.

Since I wasn't doing heavy wheeling with that truck, I had installed a 14 bolt SF. The combo u-joint I used was a Spicer 1310-1350 Part# 5-460X or O’Reilly’s – Precision U-joint Part# 348 (3.219 / 1.062 to 3.625 / 1.188). I'm not sure if it's the same for a 14 bolt FF.

 

[BigBlackChevy77]

I've done a couple of 1/2 ton to 3/4 ton axle swaps. The last one I did was on a '79 K15. My truck was already lifted when I purchased it, so when I install the 14 bolt, I had to have the driveshaft shortened since the pumpkin is larger than a 12 bolt. You will need U-bolts for a 3/4 ton axle and the spring plates as the 3/4 ton has larger diameter tubes. I think I also had to shorten my parking brake cable too.

Since I wasn't doing heavy wheeling with that truck, I had installed a 14 bolt SF. The combo u-joint I used was a Spicer 1310-1350 Part# 5-460X or O’Reilly’s – Precision U-joint Part# 348 (3.219 / 1.062 to 3.625 / 1.188). I'm not sure if it's the same for a 14 bolt FF.

Damn so I will have to shorten my driveshaft... will I run into any issues because it was from a Burbank going into a pickup or that it was from a 2wd going into a 4wd ?

 

[Craig 85]

Damn so I will have to shorten my driveshaft... will I run into any issues because it was from a Burbank going into a pickup or that it was from a 2wd going into a 4wd ?

I was kinda of surprised when I installed mine too. The 14 bolts from 3/4 tons are all the same 2 or 4WD. The parking brakes cable may be different lengths. When I did the swap on my '77 K5 I found out that some early model 14 bolts came with 11" drums, not the standard 13". It's been about 5 years since I did the swap, but I don't recall any issues coming up. I got lucky with the speedo. My truck had 3.08 gears and the 3/4 ton axles had 4.10's. I only had to remove the speedo cable adapter on the transfer case and my speedo was reading correct.

I forgot to mention, I used a 3/4 ton master cylinder from the same year truck, but was able to keep the same booster.

 

[BigBlackChevy77]

I was kinda of surprised when I installed mine too. The 14 bolts from 3/4 tons are all the same 2 or 4WD. The parking brakes cable may be different lengths. When I did the swap on my '77 K5 I found out that some early model 14 bolts came with 11" drums, not the standard 13". It's been about 5 years since I did the swap, but I don't recall any issues coming up. I got lucky with the speedo. My truck had 3.08 gears and the 3/4 ton axles had 4.10's. I only had to remove the speedo cable adapter on the transfer case and my speedo was reading correct.

I forgot to mention, I used a 3/4 ton master cylinder from the same year truck, but was able to keep the same booster.

Gotcha well thanks a ton sir ! Is there a chance I won't have to mess with driveshaft length ?

 

[bucket]

Gotcha well thanks a ton sir ! Is there a chance I won't have to mess with driveshaft length ?

Might not have to. Due to the design of the 14ff, the pinion is a bit stubbier compared to the 14sf. Iirc of course.

 

[BigBlackChevy77]

Might not have to. Due to the design of the 14ff, the pinion is a bit stubbier compared to the 14sf. Iirc of course.

Gotcha well that's be great I'd like to ditch the old 12 bolt here in a week or two and get the full float on

 

[highdesertrange]

the u-joints probably won't be the same. if it was me I would put a new yoke on the transfer case that uses the bigger u-joint and then have a new drive shaft made with the bigger u-joints. highdesertranger