will the spider gears out of a 97 sierra work in a new body 99 sierra?

 

I would say yes...they should both be 8.5 rear ends. I would change the spiders and side gears as a set if possible as they "wear" in together.

Dave

 

don't know, the NBS axle uses 8.6" ring gear and the OBS uses 8.5"

with that said I have a set of spider gears from my 2003 with about 20,000 miles in my attic, I swaped them out in favor of a Powertrax No Slip

 

The rear diff gasket is the same...general motors is notorious for keeping things interchangable (saves them money). Only real way to tell is call Mr Dealer parts man...maybe look in the catalog on GM parts direct

Dave

 

if you went with a powertrax you better hang on to those spider gears, i wish i still had mine, its going to break sooner or later