For most it is simply a matter of preference between the Gennie shifters and the Lokar units. I have a 16" Lokar in my 34, and I would assume that you would want at least a 16" or maybe even the 23" unit in a PU truck, unless your seats are mounted lower than standard.

My Lokar unit is a floor mount versus a trans mount. Just was not enough space between my floor and the top of the trans to mount the shifting unit, so the floor mount unit was the only way to go for me. Works the same as the trans mount unit, just a different location. My trans is also a TH400, but my floor is a custom stainless steel, not factory steel.

With the amount of space in and around the steering column and the trans hump, I should have gone with the column mounted shifter to give me more room on the floor. I didn't think I would like a column mount, but now I can really see the benefit of the extra leg/foot room.