NP203 fluid and which driveline oils confirmation

[idahovette]

OK, just older technology.

 

[75gmck25]

Your 14 bolt is probably a G80 Gov Lock, which operates differently than a true LSD. The G80 has a centrifugal mechanism inside that spins with the differential, and then physically moves to lock the axles if the rpm difference between axles is about 200-300 rpm. It is more of a “farmers” locker, where it’s fine to have it lock as you slowly spin up the rpm when stuck in the mud. However, it does not handle burnouts or locking suddenly on pavement, which earned it the GovBomb nickname when quite a few broke.

Bottom line - a G80 GovLock doesn’t need special LSD lube.

 

[Jordi]

Your 14 bolt is probably a G80 Gov Lock, which operates differently than a true LSD. The G80 has a centrifugal mechanism inside that spins with the differential, and then physically moves to lock the axles if the rpm difference between axles is about 200-300 rpm. It is more of a “farmers” locker, where it’s fine to have it lock as you slowly spin up the rpm when stuck in the mud. However, it does not handle burnouts or locking suddenly on pavement, which earned it the GovBomb nickname when quite a few broke.

Bottom line - a G80 GovLock doesn’t not need special LSD lube.

Without stripping it down is there anyway to tell?

I do not know how much of this truck is stock original parts or how much is mix and match from other trucks.

 

[75gmck25]

A Gov-Lock differential is different inside, but I don't know how to tell from the outside. I think you will have to pull the cover and look at it.

With GM positraction differentials (does it also work with a G80?) you can determine if it is a Posi by jacking up both wheels and turning one side. This is one method. https://motorriderz.com/how-to-tell-if-you-have-a-posi-rear-end/