The transmission is mounted in the car, fully supported on rubber mounts! I don't have any pictures of it completely mounted, but here's a few snaps of today's progress.

I bought some engine mounts from a Mitsubishi Outlander to support the front of my transmission. They're mounted on either side of the transmission and bolt directly to a plate that bolts to the bellhousing and holds the shaft locking piece.

These pictures were taken before it was all welded together. The welds came out beautifully thanks to my metalworking guru friend. I'll take photos of the finished welded parts and the transmission plate all mounted in next time I work on it (probably Thanksgiving weekend). The driveshaft adapter has been installed and fits very nicely. Everything slides on nice and smooth. A few notes about the transmission

output flange though:

• The protruding shaft is 16mm dia. The protruding shaft on the BMW transmission was 14mm diameter. The hole it goes in to is rubber and I was able to get it to fit with some lube and by pulling it together with the bolts. No modification was needed.
• The output flange has holes recessed in to it. This prevents me from fully tightening the bolts to these flanges as the inner bushing pushes out in to the hole when I try to tighten the bolt. I'll have to either put a washer between the output flange and the adapter plate, adding the thickness of the washer to the length of the transmission, or find washers that will fit in to the recessed hole and drill the middle of them out to 12mm. I'm leaning towards the latter.

For anyone who wants it, the I've uploaded the DXF file for the transmission adapter here: https://dl.dropboxusercontent.com/u/301235/E46/105 to 96 adapter circle.DXF. This adapts the 96mm bolt-circle flange of the BMW driveshaft to the 105mm bolt-circle flange of the Lexus transmission.

It's designed to use these bushings (http://www.revshift.com/product-p/pfx-frk.htm) and be milled out of 3/4" aluminum.