Get over to the Gallery and check out the pic of my 46 (Jim Merritt's) with 89 Ford Ranger extended cab, split bench. This seat was meant to be in the 46 narrow cab and the extended cab version does not have the high back head rest.
When I put the stock gas tank back in I made a 2" wooden platform on top of the tank surround to mount this new seat. I carved out a slot on the passenger side for the gas filler pipe to exit, easy deal. I could email more pics if needed.