[COE Dan]

burnette,

I can't say for sure but I think the 1940-44 mechanically shifted axles are the same as the 45-47 vacuum shifted axles with one difference: the shift arm is either different or mounted backwards. I don't think this matters with keeping the axle in high or low gear.

Reference the attached cutaway of the 2-speed axle:
No.23 is the shift fork shaft - it appears star-shaped here as you're looking topdown (end-on) the shaft) - this is what your shifter will move
No.24 is the shift fork
No.25 is the shift fork plunger
No.26 is the shift fork cover

Note that the cover has 2 detents in it. The shaft, when moved by the lever or vacuum unit, will overcome the spring tension in the plunger and pop the shift fork over to the other position. Wear in the shift fork cover and/or plunger and/or a weak plunger spring may cause the axle to shift without input. I'd check these parts when installing your axle.

That's how I think the axle is supposed to work. Hope this helps.

Dan