I have 79 F250 that I've changed the motor in from a 300 6 cyl. to 351m and I can't get the motor to turn over I don't know if I should have changed trans. also or if I should have just changed flywheels but never the less I need help! Any help will be greatly appreciated! I've done some research and it looks to be a c6 transmission.

 

Can you tell by sound if the starter drive is engaging into the flex plate, or flywheel ring gear?

 

Even if the tranny did bolt on, its likely the 351 will rip it up pretty quick. Being a 250, the frame/suspension PROBABLY are ok but it will still need an alignment for the large increase in weight on the front end. I miss my 79 F250 460, they don't make them like they used to. Also, you may need a larger radiator.

 

Would changing from the 300 to the 351m require a new bellhousing? Maybe I'm wrong, though.

 

I can't say for sure but I would plan on it