LOL, i posted this last night and assumed it's where this question came from.
http://www.ls1truck.com/forums/perfo...rs-77-c10.html
I haven't known of anyone personally who has used them but the larger tube headers are nicer than the common 1 3/4 everyone else has.
You'll prolly have to contact them about the fitment questions or maybe order them and return if they won't work.
I know the engine compartment is huge in those trucks! Would you be able to alter the angle on the motor mounts to get headers to tuck??