AH vs AM transaxle - any difference apart from the obvious?

[mj2k]

I've got two transaxles and I was planning to put the strongest one back in the car, unless there's no difference internally apart from the ring and pinion.

One's an AH gearbox (so 4.125 diff) with no reverse switch

The other's an AM (4.375) with reverse switch.

Since it's going to be used with an EV motor (so all torque available from 0 rpm) I'm tempted to put in the AM since that'll put less strain on the internal components (lower ratio means there will be less resistance), but if the AH is stronger I'll obviously go with that.

I can't find any details about differences between the AH and the AM, so if anyone's got any thoughts, it'd be great to know. Thanks

[NJ John]

4:12 is stronger than the 4:37. 3:88 is stronger than the 4:12. With all that instant torque, I would think the higher(lower number) ratio would be what your looking for.
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[mj2k]

Just checked the casings - they've got identical part numbers and are the 'twin diff cover' type, so aside from the diff crownwheel are identical internally. And I know the AH is a decently quiet box since I've driven with that one fitted, whereas the AM is more of an unknown quantity - apparently it was good when last used 10 years ago. Also the 4.125 ratio seems a better match for the motor's "power band", if 4th is used as an overdrive.

Might as well swap over the rear cover if possible so I get the reverse switch on the AH gearbox, and stick to that since neither is going to last longer than the other, and better the devil you know...