I am running a '93 silverado nv4500 on a th400 cross member with a poly mount designed for the silverado. The only thing I had to do was move the cross member up about an inch and a half and redrill the holes. The mounts that go to the top of the frame are quite a paint to drill out with the body on. The holes for the mount are the same.
This mount
http://www.summitracing.com/parts/pt...93/model/c2500