The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > All 4x4 Tech & Off Roading

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 09-10-2020, 05:45 PM   #1
Mark65
Registered User
 
Join Date: Jan 2017
Location: Vanc wa
Posts: 2
Swap F&R diff between 76 and 81 truck

I have a 1976 K25 parts truck and wish to swat the F&R differentials into my 1981 K20 truck. My question is this doable or do I need to also change drivelines? The trucks have different transfer cases too.
Thanks for any help you can provide in this project
Mark65 is offline   Reply With Quote
Old 09-11-2020, 11:17 AM   #2
kwmech
Senior Member
 
Join Date: Mar 2003
Location: Colfax-California
Posts: 8,356
Re: Swap F&R diff between 76 and 81 truck

Axles are very doable, shaft lengths would depend. The one that may give you an issue would be the front
kwmech is offline   Reply With Quote
Old 09-11-2020, 12:35 PM   #3
57taskforce
All about them K’s
 
57taskforce's Avatar
 
Join Date: Jun 2014
Location: Farmington, New Mexico
Posts: 6,170
Re: Swap F&R diff between 76 and 81 truck

It should be a pretty straightforward swap. I don’t believe you’ll have drive shaft issues but a tape measure would confirm one way or the other.
__________________
Tyler
'57 3100 http://67-72chevytrucks.com/vboard/s...d.php?t=813888
'72 K20 Cheyenne http://67-72chevytrucks.com/vboard/s...d.php?t=662879
‘69 K10 SWB http://67-72chevytrucks.com/vboard/s...d.php?t=805206
'98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 315/75/16's
‘87 IROC-Z all original 50K mile survivor TPI 305 IROC Blue
‘10 Camaro 2SS/RS Aqua Blue Metallic #93 -version 2.0
57taskforce is offline   Reply With Quote
Old 09-11-2020, 02:55 PM   #4
Mark65
Registered User
 
Join Date: Jan 2017
Location: Vanc wa
Posts: 2
Re: Swap F&R diff between 76 and 81 truck

Thanks all for the info
Mark65 is offline   Reply With Quote
Old 09-12-2020, 02:10 AM   #5
Zoomad75
K5Camper
 
Zoomad75's Avatar
 
Join Date: Mar 2004
Location: Pueblo, CO
Posts: 1,513
Re: Swap F&R diff between 76 and 81 truck

Depends on the t-case situation. The axles bolt in. The earlier front shaft should be the Saginaw style where you have individual saddles for the u-joint on the front output yoke. Also the rear shaft on the early one might be fixed yoke if it's a 205.

The front on the later truck will most likely have a flange style mount for the cv to the front output of the t-case. Also, if the later truck has a 208 it most likely is a slip yoke rear output.

But as long as the size of the u-joint is the same at the front and rear diffs as the axles you are pulling out you should be able to re-use the shafts.
__________________
Rob Z.
1975 K5 350/465/205/D44/12b 4" lift on 35's- RIP
1991 K5 8.1L/NV4500/241/D44/14b FWC Camper
Zoomad75 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 05:14 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com