[lukecp]

327 powered truck usually had 3.07 gears unless optioned otherwise. 283 and 6-cylinder trucks usually had 3.73. The only way to know for sure is to pop the cover, and the number of teeth will be stamped on the ring gear. 41-11 is 3.73, 43-14 is 3.07.

You can get your current rearend rebuilt, and i reccomend this if you can afford it. When you get a junkyard rear you chance that it will be worn out and have a limited lifespan. I learned this over Christmas when i put a used rear in my truck and it turned out to be junk. Although, a 12-bolt is a tough rear and i am sure it is possible to find a good one. Swapping rears is an easy job, even for a beginner. You can get it done in a day or two no problem for the first time.

Anyway, he parts (ring and pinion plus install kit) run around $275 for decent pieces. Now, the labor is what gets you. Rebuilding rearend is somewhat of a specialtly, and not many shops do it. So it may be hard to find someone who will do it for you.