E-mail Zalman, or go to Thermalright's site and see if the XP-120 fits on your board (I'd imagine they're roughly the same size, since they both take 120mm fans).
Edit: Thermalright's XP-120 obscures the first PCIe slot with its heatpipes, but it looks like that's the PCIe x4 slot, which is used by nothing that I know of ATM. On the Ultra-D you also have two PCIe x16 slots according to that picture anyway.