[Formerly Steve Wilkinson]

Nope, no photos, and it's gone--sold. It was a T-shaped apparatus, the ends of the T crossbar folded about 35 degrees forward on each end to "cup" the seatback, and the vertical part of the T extended down to about the bottom of my spine. The T was welded and gusseted to a heavy tube that passed through a collar bolted to the rollbar's horizontal crossmember, with a couple of through-bolt holes so the position of the device vis-a-vis the seatback could be set for me, or for my shorter daughter. (My wife's a serious rock-, ice- and mountain-climber; she has no time for such nerdy activities as driving in DEs...)

The inside--toward the seatback--part of the device was padded with a 3/4"-thick layer of energy-absorbing foam sheet, sort of like good roll-bar padding but much denser and not bendable.

I've seen one-size-fits-all commercial seatback supports--I think Brey-Krause sells one--but they're about the size of dessert plates and seem to assume a super-strong, non-breakable seatback. Which is a pretty expensive seat, if it exists...