PLEASE HELP I bought a truck without a motor but a mt653 still installed, found another 429 and attempted to install it finding that the flex plate is different, does anyone know what flexplate I may need???

 

There's no MT653 Allison listed in the 1980/89 Ford Heavy Truck Parts Catalog.

What I do see is for the flexplate is: MT643 & MT650.

F7HZ-6375-DA (replaced D9HZ-6375-G) .. Flexplate - Use with MT643/650 Trans Matics (Allison) / Obsolete

1979/ 370/429.

No Ford dealer or obsolete parts vendor has any.
-------------------------------------------------------
D9HZ-6375-G ~ Last MSRP: $256.10 / Dealer net cost: $153.66

HIGH BUCK! BOB ALLEN FORD in Overland Park KS has 1 = 913-381-2999.

Be prepared for sticker shock, this "snake" wants mega-bucks for obsolete parts and he's the only source that has it.