[Dave at Pelican Parts]

First, please note that this is an old discussion that was resurrected by a single-post user. Not sure why.

Second, the 915 conversion can work just fine. I've driven one that worked pretty well, at least in the lower 3 gears. The WEVO setup would probably have worked even better; those guys know how to make stuff that just plain works. You do have to fab up the rear shift rod if you use their setup, though.

Third, you have to machine the inside of the diff housing to flip the ring gear on a 930 box. Not a lot, happily, and there are places that know how to do it--but it is not a simple bolt-up affair. There's also the minor issue of the box not bolting to the chassis. You could run the 930 box upside-down, but you have to do some plumbing to make sure the oil gets where you want it to go and you may need to cut out the trunk floor to make room. Again, not a bolt-on conversion.

Alternatives exist.

There are people who run G50s upside down. An even more complex conversion; you need the short-bellhousing version, plus the hassles you have of running the 930 version upside-down. But it is quite strong...

The Boxster trans is another possibility. It's already set up for the mid-engine location, and it is reasonably strong. I think you still have to cut up the trunk floor, because it is significantly larger than the original 901-based box. But it has been done; there are even a couple of posts on this BBS showing one such setup. (I think one was titled "the ultimate solution for vague shifting" or something like that.)

--DD