Hi liveleff, welcome to the Club.

You have a Z18 "Naps Z" eight spark plug engine in your 1974-1978 120Y (body type B210)?

The Z-type engines can use transmissions from L-type engines (510, 610, 710, pickup trucks, etc), they just sit slightly off-level (did I get that right?). You may need to modify the driveshaft, so measure the length of your existing transmission and count the number of splines on the output shaft.