steering box woes

[crosby]

I have an 05 K2500HD (gas) and to replace the pitman arm, I pulled the steering box. Trying to put it back on just now, I can't get the three bolts through the frame to tighten - there's about half an inch of slop on all three bolts and my big ass air gun won't move them, and nor will my breaker bar and all the alcohol in the world

I pulled the box back off and put them in by hand carefully, and it looks like the first few threads of the three bolts are eliminated/removed/flattened on purpose so you can line the box up when installing? But once the bolts start to poke through the other side of the threads on the box itself, they stop turning. I can't help but wonder if there's supposed to be a bracket, or sleeves, or something between the box and the inside of the frame? They came off pretty easily with my air gun

Thanks guys for any help you can provide - I don't mind taking a little heat if I can just get this figured out and on with my life, ha ha!