Are there any wires sticking out?
The last time I blew the RDO fuse was when I was installing a radio in, and the remote power wire touched a ground and blew the fuse.
Make sure its all wired correct, and nothing is sticking out/exposed.
Blazer Sold. Look at what I have left:
-UHaul Trailer Hitch + Receiver
-Factory 4.3L Vortec Air Box with Intake Plenum