Have a look at the pics in the first post of this thread. You will see how the swivel mates with the floor and seat.
The power mechanicals occupy most of the space between the seat and the floor. All of these s mechanicals would have to find a way to live on top of the pedestal which would probably raise the minimum seat height by 6 to 8 inches? Plus, these were tested for the weight and design of manual seats, not the extra weight of a power seat's motor mechanism.
A manual seat's tracks are mounted on top of a pedestal. When using the swivel seat base the pedestal is removed and discarded. The swivel base bolts into the same floor mounts and replaces the pedestal. The seat tracks mount to the upper part of the swivel. The seat stays at the same height as stock.
I have an embarrassing install question but I'm a little stumped. Do I need any spacers to make these seats work? My floor appears to be convex and the seat does not sit flat. I've seen some people cut out the rubber but I've already got a carpeted cab and cutting out the thin carpet wouldn't make a difference. There is also the sensor wire that crosses the hump that is being pinched. Before I space it up I was wondering if I'm missing something obvious.