[Grady Clay]

Craig,

Your 901/13 is the late ’69 901 transmission with the pressure die cast housing (called “investment” casting from the German translation – also indicating the great cost investment in the tooling).

It is geared:

1st A 11:34=3.09:1
2nd F 18:34=1.89:1
3rd M 22:29=1.32:1
4th S 25:26=1.04:1
5th Z 29:23=0.79:1
with a 7:31 ring & pinion

The S/N is consistent with everything else.

Please check to see if there are any other numbers.

This was equipped with the “simplified differential” and you should confirm it has been updated. Do a Pelican search on “simplified differential” and don’t neglect this – bad things can happen.

How about the other questions?
The more info, the better we can help.

Best,
Grady