MAF has a couple of kits. Mark's adapters also lists some.
Its easy to make your own also. I used alluminum bar stock cut to desired lengh and drilled. The next itme I do one though I'm going to use the fat kids sugestion of using boat rollers cut to desired lengh, already has a hole in it.
What would be slick is to find a source for longer metric bolts that have the tapered tip like the factory uses.