I'm desperately looking for a good used M41 tranny for sale (at less than an outrageous price ( I'm broke! )). I have a good overdrive unit but the tranny on my 1800ES (daily driver) bit it a couple of weeks ago. Can the O/D unit be installed on an M40? If so, what does that involve? I'm 75% sure the answer is no but the other 25% wonders.

The gearbox internals are the same in terms of gears. The major difference is that the mainshaft in an M41 is longer in order to drive the overdrive. There is nothing to stop you repairing a worn out gearbox with better internals from an M40 providing the mainshaft in the M41 is OK.

Be aware though that very late M40/41 boxes were different. They had a bigger layshaft axle, revised reverse gear design and altered ratios. If you get an early box you cannot fit those internals into a late case or vise versa. You could however fit the late mainshaft to the earlier M40 keeping gears, layshaft assembly and case together.

Mainshafts for D and J type overdrives are different, so the mainshaft needs to match the overdrive. An 1800ES uses a J type OD.

The collar that takes the overdrive will physically fit onto any age of box.


Regards


Pete

I thought the tail shaft of the M41 was SHORTER because of the presence of the OD unit in place of the M40's tail stock casing. Am I goofed-up?

The tailshaft on the M41 sticks out to the middle of the OD unit,
so it is definitely looooooonger! The rear housing on an M40 is not
even as long as the OD adaptor.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma