I snapped off some of the spider gears in the rear end of my Astro. My mechanic said he can fix it if i get the parts. My question is would a whole rear from the Junk yard be better than piecing out a rear from the junkyard. Also how do i found the gear ratio and which rears are compatible with with this van. Ive heard some Camaros and I believe the S-10. The 8th letter of the Vin is a W

 

You should have a GM 7.6" rear with 28 spline axles, I don't know what other vehicles use the same one, but any Astro/Safari from 89 - 2005 should have the same one.
I would take the whole carrier and use your old ring gear if it is OK. That way you don't need to worry about matching the gear ratio when you're hunting at the junkyard.

 

Cruddybrown, It might be time to put in a Powertrax No-Slip locker in. Just a thought. Jim

 

Yeah, grabbing a whole rear can be cheaper than grabbing the contents of the pumpkin.

Gary is right, if you swap the entire axle assembly only an Asto/Safari one fits. According to Randy's Pinion and Gear the 7.6"/28 spline gear assemblies are also used in the rear of the Isuzu Rodeo and in the front of the Hummer H3 and Chevy Trailblazer, so those axles assembly could be bought to use their pumpkin internals.

To find your stock gear ratio look for your RPO codes.
The two most common are:
GU5 : AXLE REAR, 3.23 RATIO
GU6 : AXLE REAR, 3.42 RATIO

 

I paid $40. for the whole carrier and internals at the local U Pull It for a 8.5" 10 bolt
The locker you are talking about cost a few hundred.

 

Don't forget about the money that will be spent on getting it in properly. The Powertrax No Slip that I suggested, requires no ring & pinion removal, and can be done by the average Joe. Let me know how much the Expert Rear End Man charges to pull out the old guts, and install the new from the junk yard ones. Then I'll tell you how much my brand new Powertrax No Slip locker cost for me to put in. Jim