A rotor from a 2003 and newer van/2000 and newer truck will slide over the hub of early HO52s with the front mount drums. Not for sure on the rear mount drum hubs.
I've been working on a disc kit with components from an 03 van. The only real obstacle I've encountered is finding a machine shop that will cut some flanges for me. I'm almost to the point of buying some plate steel and a bunch of hole saws and doing it myself.
All the components are also availible from GM and are priced reasonably. BTW-the truck brakes are priced better than the van.
Here's what it looks like.
http://s1074.photobucket.com/user/wh...tml?sort=6&o=1