91 chevy open diff swap to posi lock

I have a 91 chevy with a open diff i was wondering how do you tell which rear ends can you swap right in that is a posi lock. Like which trucks would be a donor truck.

There is usually a screw-mounted tag attached to the housing to indicate this. If you are looking at donor trucks and not just rear axles, you can look for the G80 option on the RPO label in the glovebox.

Also make sure you match up the gear ratio otherwise you're speedo/odo will be off. Hope this helps!

If you're just looking at the axle itself, there should be a metal tag attached to the housing with a screw identifying it as having a posi diff.

If you're looking at axles still installed on a truck, check the RPO sticker in the glovebox for the G80 option. This isn't 100% though since some owner's could swap them out, but usually they'll put a posi diff in rather than take one out for an open diff.

Acid test is to inspect it with the cover off, obviously. Hope this helps!

I have a 2000 1500, the sales paper says it is a C10 but the cab has a Silverado emblem on it. How do I figure out if I have an 8.5 or 8.6 10 bolt rear? Spider gears are trashed and need this info to replace. Any help would be greatly appreciated.

I have a 2000 1500, the sales paper says it is a C10 but the cab has a Silverado emblem on it. How do I figure out if I have an 8.5 or 8.6 10 bolt rear? Spider gears are trashed and need this info to replace. Any help would be greatly appreciated.

The C10 is simply a 2WD 1/2 ton Truck. The "Silverado" emblem is just a truck line with more options than standard.

For the rear end, take the VIN to the dealer or a salvage yard. They may be able to tell what you have. Also as posted above look for the RPO code in the glove box or the tag on the differential.