How many types of Sherman transmission (not the cover they reside in but the actual box that connects to the driveshaft) are out there including the M40 with HVSS? Haven't exactly been finding much information on them, the SoS book doesn't talk much about the subject.

Do you mean the gearbox? I am aware of two versions of that, with transmission parking brake and without. I don't think the diff varied mechanically, although since it was integral with the cover, there would have been three versions.

I'm sure Kurt would know though.

I do mean the gearbox. Have encountered a sub variant of the later transmission that looks rather unusual with what the description calls a generator mounted on the cover that goes over the upper rear of the gearbox.

Turns out my first hunch was right from the start.

We all know the following to be the first type:



Followed by this one:



... there IS however the following type also, which the Tankograd book confirms to be for the M40 with 155mm howitzer: