Hitch Depot USA seems to have good prices and
free shipping.
http://www.hitchdepotusa.com/
Class V Hitch - #15520 (Qty: 1) $170.28
Wiring (55335 ) (Qty: 1) $36.01
additionally I bought:
Multi-Function Sockets w/ Backup Alarm (57102 7-Way Round RV And 4-Way Flat Adapts From Existing 4-Way Flat) (Qty: 1) $26.29
My '97 GMC Savana Diesel specs show max tongue weight:
750 lbs with the 3.73 axle GCWR 13,000 lbs
900 lbs with the 4.10 axle GCWR 14,500 lbs
I have the 3.73 axle
(RPO code GT4 listed Service Parts Identification (SPID) label on the passenger door)
So a Class IV hitch would have been more than enough but the Class V cost less and only weighs 1lb more. The Class V has Gross Load Capacity Tongue Weight of 1500 lbs - way more than what the van can actually take.