I had an 81 stepside years ago, and a installed a B&M
Quicksilver into the seat right next to me. In park the shifter ball was right on the edge of the seat, and in drive it was right in the middle about 4" high, right where your hand rests comfortably. It was surprisingly easy to do, and it worked great. Sorry I don't have any pics, the truck was stolen 10 years ago.
I'm planning on doing this again in my 70.