Can someone tell me what pinion yoke is used on the 2001 2500HD and where I can purchase on?

This is the yoke on the rear diff that the drive shaft bolts up to via the u joints.

Thanks so much

I would try Fleet Pride. They specialize in heavy duty truck parts. Here's their website www.fleetpride.com (http://www.fleetpride.com) I know they do driveline work and may have something in stock or readily available.

Gee, do you think a Chevrolet Dealer could get you one?

You may also be able to get that part from a NAPA store as well. Or try the dealer.