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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Rear Drivelines, Drive Axles and Gearing => Topic started by: Mark on September 10, 2020, 06:06:39 PM

Title: Swap F&R diff between 76 K25 and 81 K20 truck
Post by: Mark on September 10, 2020, 06:06:39 PM

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

Title: Re: Swap F&R diff between 76 K25 and 81 K20 truck
Post by: JohnnyPopper on September 11, 2020, 02:37:07 PM

It will probably work, but what are you gaining?

Different ratio, lower miles?

If the 76 has a NP203 transfer case you'll want to install a part time Kit and locking hubs, or expect already bad mileage to be worse.

Are the wheel bases the same?

Inquiring minds want to know...