i have recently aquired a 2wd 1988 F-150 with the 4.9L I6 and M50D 5sp tranny. to me this is an ideal project truck.
i want to swap in a 351 or a 460 depending on whether or not i can find the latter cheap enough.
anyway, i know the stock tranny is light duty, and probably couldn't handle a respectable amount of torque thrown at it for an extended period of time. do you think it would be better to have it rebuilt and beefed up, or would i just be better off finding a T-5 from a mustang or a 5spd from a 2wd superduty and try and make that work?

 

I would rather have the m5od over a t5 in a truck. I would suggest going to an old toploader or something similar. The zf would be nice behind the 460.
Alan

 

would the stock M50D be ok behind a 351? or should i have it rebuilt and beefed up a bit do you think?

 

I'm not sure of much you can do to strengthen one of those. It will work just don't try to force it into gears. The clutch will be the thing you need to upgrade.
Alan