No one makes a crossmember. Not that I know of. It's a shame. Luckily it's not the hardest part to make or have made from a basic print. Get the engine/trans in place and aligned, then take measurements. The width will be obvious but the offset (height difference between subframe mounts and trans mount) should be measured carefully. When in doubt, built it a hair on the low side so that you can shim the mount for proper driveshaft angle.
If you can't fabricate post pix and a print. One of us will be able to help you out (maybe Tyler at American Touring Specialties will hook you up.)