I'm replacing my clutch in a 1980 F250 4X4 with 351M and NP 435.
There is a lot of hardened black crud on the inside of the bellhousing so I am going to replace the trans seal, I already replaced the engine rear main seal. I can't seem to find the gasket that goes between the front bearing retainer and trans case, can I just make a gasket out of a roll of gasket material available at Pep Boys?

 

Go to a driveline supply store. The NP435 is very common so they should have tons of those gaskets lying around.

 

These gaskets come in different thicknesses to set the preload on the bearing. If your trans is set up correctly get a gasket of the same thickness, take your old one down to the drive line shop so they can measure the thickness. After you torque the bearing retainer in use a dial indicator to check end play if you can. If you search this forum on NP 435 there are some posts on this.

Wes

 

Thanks for the info, I didn't know the thickness was so important. I think I'll just leave it as is, upon closer inspection I don't think there was a leak from the transmission gasket or seal. I think it was the rear main seal that was leaking (almost half of it was missing) and splattered oil all over inside the bellhousing.