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Looks like a toploader set up for three plus overdrive. Ford transmission, not Warner.

 

D9Z has something to do with a 79 mustang, eh?

 

That would be an SROD (Single Rail Overdrive) 4 speed. They were used in a number of late 70's to early eighties FOMOCO products, Granadas, Fox bodies ( Mustang.Capri..Fairmont/Zephyr..T-Bird/Cougar,etc)
They were not particularily stout (at least not behind the V-8's)....I would look for a 5 spd B-W from a newer car, you will end up with a stouter peice, with better parts availability,etc.


HTH
James