Do I need to check backlash after replacing the diff bearing?

Backlash and side bearing preload.

The factory shims that are in there now are cast iron, they'll break if you try to reinstall them. Service shims are steel and you'll need an assortment to choose from.

Seconded, AAR!

Given the original posters question, did you think he would have one to use?

AFAIK, and I may be way wrong, the spreader isn't even part of current GM service procedure for the passenger car axles. I'd gladly defer to Ian since he does this every day in that particular setting...

Ian is an excellent source....Setting up rearends was something I always managed to dodge... it isnt rocket science, but I have great respect for the need to do it correctly. And I never had the tools to do it correctly, so -for the very few instances we had to deal with differential service - we sent them out.

It does if there are acceptable alternative methods.

I already stated that.

It can be done correctly if he uses the steel service shims that are available from GM and/or any number of aftermarket vendors.

I fail to see the similarity between a machining operation and an assembly operation.

Not necessarily.

That may be true regarding the original assemble at the factory, but necessarily true at the dealership level and certainly not true if one reads the instructions supplied with just about any aftermarket gear set/differential assembly. If one calls and queries Randy's Ring & Pinion, they will actually tell you -not- to use a case spreader on any GM axle including a 12 bolt.

FWD is a whole different animal.

Careful who you name drop.

Hobby stocks, eh?

Speaking of snobbish, i suppose you look down your nose at the products sold by Mark Williams Enterprises also.

The last racer who didn't stiff me died in a plane crash years ago.

So, you call the guys at Richmond Gear often?