I did not real try to source the transfer case seal, we just knocked it out, it looked ok so we just put it back. I had full intention of replacing it once the testing was completed, but now that its in the rally car, it will more than likely stay there until it starts to leaks. At some point I am going to try and put together a bearing and seal kit for the transfer case. The seal I am supplying for the adapter housing is the same one the 4WD version off the 6L80 uses. The 2WD and the 4WD case are the same part so there is a place for the seal to go. My initial plan was to just cut the thread off the 2WD output shaft bang the transmission rear seal and a couple off small welsh plugs into the transmission housing. This would have made my adapter housing much less complicated to machine, but as with all things, the 2WD output shaft has a different profile to the 4WD shaft where the seal sits. So plan "B" move the transmission output seal into my adapter housing and add the seal area on my new transfer case input shaft. Unfortunately whilst the transfer case is the same, on the 5L50, the STD adapter housing is quite different, so my adapter will not bolt up to a 5L50. I was planning on doing a V6 version to replace the 5L50, which may have been the same as the BMW, with a 6L45 or 6L50, but nothing off what I have done fits. I have shelved this development as the adapter housing is different, the 6L45/50 is a smaller housing than the 6L80 and the transfer case input shaft is different, the 6L45/50 have different output splines to the 6L80. I did have one late night though that I could put the 6L80E behind the V6, with the V6 bolted in and the 6L80 bolted in there is a convenient 28mm gap, between the two, that I could have made adapter plates for the engine to transmission case, the torque converter to flex plate and then some sort off spigot for the torque converter nose to sit in. I talked to my automatic transmission guy and he does no believe the V6 would be able to drive the V8 torque converter effectively. So this idea disappeared as quickly as it came. Cheers Clive