What are the exact specs of the rearend of my truck? I have a 99 5.3 extended cab, the reason i want to know is that I have a friend that has a set of 3.73's sitting in his garage that are new that he will give to me i just need to make sure that they fit. They are for an older Chevy truck, an '85 I think. Thanks for the help.

 

Well are those gears for a 1/2 ton, 3/4 ton, or 1 ton truck?

If they are for a 1/2 ton they should work, you will need a spacer (I think) as the new truck rear axles are 8.625". Your rear axle is also has 30 spline axles.

 

They were for a 1/2 ton truck. What would the spacer be for? s using a spacer a good way to go or should i just get some gears that are made for my truck?

 

I think that spacer is used as all gear sets are made for a 8.5" and the new ones are 8.625". It should be fine, just call a drive train place like Randy's Ring & Pinion for that spacer. www.ring-pinion.com