What powers wagon head's suburban?

Didn't want to take seesko's thread off topic(2 door wagon/sedan deliveries), so decided to start a new one. Wagon Head and myself haven't really been formally introduced, but I see his suburban around local car shows and talked with him about the engine in his ride at a topeka show. The first time I walked past the engine compartment, I had to stop to figure out what the powerplant was. It's not too much of a brain teaser, but his disguise was pretty clever. He watched me scratch my head for a little bit and then filled me in, and we had a good laugh.
Bit of a slow day at work today, so I thought I'd give everyone here a look at it to figure it out. What is it?

 

Looks like a late-model 6.0 or so, with VC adapters

 

yeah it's a late model truck motor, with a 4bbl carb intake and old cad valve covers glued on

 

Just bumping it up to the top so wagon head can spill the beans.

 

Yep, I'm busted. It's a 6.0 that has been massaged a little, 850 Holley, Coil Pac's are inside the frame rails so the plug wires appear to be "correct". The original 6.0 valve covers are under the Caddy covers and we welded tabs and drilled & tapped them to screw the Cad valve covers on. Thanks for playin! Hope it was fun. You started it Jay!