Is it possible to purchase from ATI (or elsewhere I guess) single slot back-planes for the X1950XTX and X1950 CF Master cards?

I am currently thinking of watercooling my PC and want to re-organise what cards are in what slots.....the watercooling will allow the cards to fit in a single slot but unless I can get new back-planes, the cards will still block an additional slot each.

TIA