I'm considering an A 500 4 speed overdrive for a 72 Duster

Who here has experience with this transmission?
I do know a few things about this transmission. I know that it is based on the 904 series. I would expect it to also then be shorter and lighter than a 518 model. The early models were hydraulic so they require no controller to run. I am guessing that they would still require floor pan modifications but surely less than with a 518 installed there.
I'm curious if they retained the same low first gear that the later 904s had. If so, that would make for a better gear spread than the 518 while taking less HP to operate.
The Duster currently has a slipping 904. I am thinking of using a Ford 8.8 axle in it with 3.73 gears so the overdrive would be a great addition.

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The car has a mild 360 4 barrel that runs great.