flywheel question

hey all, just wondering...I am buying an 81 F150 4x4, 4speed...the flywheel may need to be changed...I have a 79 small block ford V8, not sure if 302 or 351, but will the flywheels interchange? If not, why? I am thinking it may be they are balanced different, but thought I would ask...thanks for the help
Jenn

The flywheels will interchange, the balance is the same for the 302, 351W. There were/are several flywheels vailable , just make sure its the same dia , same # of teeth, and if its automatic, make sure the bolt holes for the convertor are correct. The 6 cyl flywheels will look identical, and will fit, but they balance different. Alot of late model engines are zero-balance, the bolt holes will line up in all positions. These will only line up in one spot, but be careful, there is one spot where all will line up but one, and its close enuff it will go if you force it, and it will vibrate. Make sure you can screw em all in with your fingers

Probally not.Ford does this:a 6 month change on interchangeable parts.Go to an auto salvage yard and have them look it up in an interchange book called a Hollander.

ATP Inc. flywheel part #s for Ford F Series trucks, also fits cars, vans, and Bronco.

Aotomatic transmission:
302 engine:
1969-79 all part# Z-105 with c-6 part # z-110
with AOT thru 1981 part # z-133 1982-96 part # z-157
with E4od part #z-193

351w engine:
1977-81 all part # z-110
1982-96 w/C-6 part # z-105 and z-110 the difference being additional bolt holes for other torque convertors
all with E40d part# z-193

Manual transmissions: 289 thru 351w 1965 thru 1993
only two basic part #s z-250 13.25" 157 teeth
z-257 14.313" 164 teeth
They may change parts every six months now, but they didnt then.