[Walt Fricke]

Right - same clutch and PP and compatible flywheel diameter/mounting/ring gear etc. Tranny input shaft splines are different than the 915s, so clutch disk has to match? Or did that happen at some other time?

It is the unique 70-71 clutch release lever system which I don't know from experience can just be installed on a 901 case, or whether some adaptation is required.

The cable part I know can be made to work. It performs quite a trick - you use a flexible cable to push, not to pull, a lever. The end of the cable is attached to an extension bolted to the transmission. The Bourdon tube presses against the end of the release lever. When you step on the clutch pedal, that takes the curve out of the flexible Bourdon tube, which causes it to push backward on the lever. The pivot inside causes the other end of the lever, which connects to the TOB, to move forward, releasing the pressure. One hears stories about problems with the lever's attachment to the ball pivot, or the ball pivot itself.

The 915 system looks simpler and more robust.