GM-GMC: gear ratio, rear axle ratio, chev truck

Question
This is not a diesel question, but here goes. My nephew has a 1991 Chev. truck, the 2500. It's four wheel drive, automatic, 6 lugs or plugs or something (vs 8), and drum brakes. His rear end went out, and I am trying to find a new one to replace it. I am a girl, and I have no idea what I am talking about. When I call the junk yards looking for it, they tell me they need to know the gear ratio. How do I find it? One guy had me look in the glove box and had me read a code that started with the letter G. It was GT5. Doea that mean anything? If not, where do I find it? Is there any other information I need to know to give to these guys?

THANK YOU! I feel bad, I just made women look horrible!

Answer
Angel,

Believe me, you are doing better than most men when it comes to this subject!

GT5 is a production code for a 4.10 to 1 rear axle ratio.  That means that it takes 4.1 turns of the driveshaft to get one turn out of the rear wheels.

Try www.car-part.com for used parts.  It is a good site to locate them.  Remember, though, that a rear axle is heavy and shipping it might cost a lot of money.  Try to find one close to home so that it can be picked up.