[Russell]

If your cab has the same big "bump" in the floor under the seat just behind the hump, then your job is real easy. Just go find an unboltable high hump that has the proper holes in it already, lay it down overtop of the low hump, drill out the holes, then cut the low hump out leaving about an inch of metal past the holes you drilled.

Then just tack weld some bolts to the underside of your cab around the holes, and bolt it in with washers just like the factory did. Just make sure that you paint the bare metal with something, then use some silicone to seal the high hump down.

My 80 didn't have that transfercase hump, and I was forced to cut the whole floor out, and bolt in a new peice. It didn't turn out all that well, so I bought a new cab to replace it with that has the transfercase hump, and a low hump for the transmission to do exactly what I described to you.