Does anyone know if the AWD rear differential has the same gear ratios as the RWD Astro? Or, is there any easy way for me to determine if the one that was given to me will work or not? It came off of a RWD, same year with the same engine. Any help would be appreciated. Tom

 

Gary, thank you for your response. This is our second Astro, it's a 1994 AWD with the 4.3 engine, and 165,000 miles.
A few months back, I had a plastic tarp wrap itself around the driveshaft and press out the seal in the rear end. Since it was such a mess, I took it to a shop for repair, and they replaced the seal but may not have got the preload right, since after only another 1000 miles, the rear end started to howl (on vacation, of course). I had a rear end from a 1994 rear drive Astro cargo given to me. But I don't feel confident installing it until I know for sure it is the correct axle. I haven't been able to find any markings on either one. As far as I know, they are both OEM. Thanks for your help!

 

All of the 2WD vans I've owned (5) were 3.23 rears, my AWD vans (2) have been 3.42.

Since you don't have the cargo van to read its RPO codes, you can look at the axle tube code. This should be on the front side of axle housing next to the diff on the passenger side. There are lots of numbers and lots of code definitions. It's the first three characters are what identify the ratio and whether the diff was open or posi. Return with these codes from both axles and I can tell if the gears inside will work for you.

 

Well thanks for your help Gary and Aaron, but after calling the Chevy dealer with the VIN's (turns out my buddy had the old VIN after all) and they said the new one and the old one were exactly the same, it didn't fit physically. The difference was in the leaf springs, the cargo had plastic (!?) and mine was more conventional, three leaf metal springs. We actually had the new one in place today and the brackets were all the wrong size. The new brackets wouldn't fit around the springs, and the old ones were too narrow. So after all that we put it back together with the bad one and I suppose I will take it to Rocky Mountain Axle and have them rebuild it.
Assuming it makes it that far. It is getting really noisy! It will be nice to have it done by pros since that is all they do.
Tom

 

Sorry things didn't go quite as planned. How far does it have to go to get to RMA?

 

Greetings,
I have a RPO code of "GU5" is that a 3.3 ratio in a 2000 Astro Cargo van. After a shoddy shop changed the seal the howling started. I have a lead on another 2000 Astro Cargo van for parts but wanted to make sure the ratios are the same. Thanks

Raanmaan

 

Here's an update on this problem with this differential for anyone who may be interested. I decided not to drive the van across town, fearing I'd damage it beyond repair. It was unbelievable how loud that sucker was, at thirty mph you could barely hear the radio over the grinding noise it made. We decided to try and swap the guts from the spare one into mine. I took the spare diff apart, and cleaned up the ring pinion and spyder gears. They were in pretty good shape, even though the cargo van showed 314,000 + miles on the odo. If it hadn't been replaced it was really still in great shape for that amount of use. When I took the bad one apart, I was surprised to find a locker type, with clutch and all. But what really shocked me was the condition it was in. The oil was clear, except some metal shavings, and all the gears were still fine. Turns out all that noise and grinding was coming from just the pinion bearing! I expected to see big chunks of ring gear falling out. That one bearing was toast, but no other damage. So, as soon as all the parts (diff & axle bearings and seals) get here, I should be ready to put the thing back together and use it. I never did find any markings on either axle indicating the ratios, but that doesn't matter at this point anymore. Thanks again for the help, I am looking forward to driving it again.

 

Thanks, I think I will.