5.0L MAC U/D pulleys fit, what size belt though???

Not sure, I would just get a string wrap it around the pulleys and then measure it, that's probably the best way to do when in doubt. Goodyear makes all kinds of lenghts. check out summit racing website you can narrow it down by size or send private message for more info.

thanks guys. i went with the string method lol. it ended up being about 4 inches less just with the smaller crank pulley.