07 Classic LBZ CC battery killer

[no moa]

I'm usually in the old truck section, but i need some help on a new truck, Anyone out there got some GMC knowledge? I'm a pretty bright guy, and usually can locate a problam and fix it. But this has got me stumped.

I have a 07 classic, with the LBZ Dmax. The thing is killing batterys in the last week. Usually in the fall, it will pull this if it sits for a couple days, but this is a kill good batts in 3 hours type thing. I have unhooked everything foreign to the truck, plow set up wires, my FD radio, etc etc.

Removed the neg cables from both batts, used a test light to see if there is a draw. There is a Huge one. The fuse block under the hood is the culprit, but we removed every fuse, maxi fuse, relay, still nothing.

We've looked for broken wires, i've pulled the block almost completely apart, i found one 50amp fuse that dims the test light, but not much, unplugged everything i could find under the dash, pulled all the dash fuses. I'm stumped, going on 3 hours now, and i've called everyone i know.

Anyone got any thoughts. I haven't started unplugging computers i guess what will be next.

Thanks
Glen