1981 'vette rear end

I have a 1981 Vette and want to change the rear end ratio. It now has a 2.87... I want a 3.55 or 3.73 rear. I'm really having a hard time finding out what kind of rear this vette has... What is it?? Is it the ole regular chevy 8.5" 10 bolt?? Or is it a Dana 44?? Does the ring gear have right hand threads or left hand threads?? Where do I get a ring & pinion and bearing kit?? Help me!

Thanks

Bob

Try contacting Randy's Ring & Pinion in CA. [http://www.ringpinion.com/] I've used them for rebuild kits/parts and they are great to deal with. Good service & prices too! They will be able to answer any questions about you're diff. If you have'nt done this type of work before, find some one with experience to help make sure pinion depth, backlash, etc. are correct or you'll be doing it again real soon!