Datsun 210 5 Speed Transmissions
There are 3 different types of 5 speeds, from the Datsun 1200, B210, 210.
Some of them may be 18 spline input shafts, I know 75-78 B210's had a 1 1/4" 24-Spline Input Shaft.
Because of the MG Conversion usage, these transmissions are very hard to come by. As an alternative, in Australia Toyota came out with a 5 Speed T5 Transmission; they are supposedly cheap and common. A company makes a custome bell housing for these trannies to fit the A-Series motors. With parts cost and shipping your probably looking at around $800 or so. I figured I would mention it as a last ditch/desperation alternative. Although, according to people on Datsun1200.com the Toyota Tranny has a much better gear ratio to suit the A-Series than the stock trannies.