Have a ?, have a 88 f700, 370 4v & also f600 1976 391, the 370 seems dead will due compression test on and see for sure, I have not looked it over real close yet, but i'm wondering if other than the exhaust will this swap work, it looks to be that it will, it seems on here that the 370 is from the 429/460 temp plate, what is the industrial 331. 361, 391 based off of, the same thing or different, i would like to put the 391 in the f700 it is strong yet, the 370 seems shot, just wandering if it will work or if anyone has experience with it, any info on this would be great, thanx alot dan

 

if you swap bell housings, or trannys, if they don't have removeable bell housings. it should work. they are completely different motors but if you have both trucks you should have everything you need

 

the 370 is from the 385 engine family (370, 429 and 460) while the 391 is derived from the FE engine family (352, 360, 390, 428, 427) etc. the 391 is just the medium truck version of the 390. not sure of exact differences between the 390 and 391 but they are closely related (much like the 370 and truck 429 are closely related to the car 429 and 460).

so basically the motor mounts, tranny's, exhaust, etc are all going to be different between the two engines. the motor mounts from the 370 won't work on the 391 along with the transmissions. if the frames are the same width between the two trucks, then you can swap the motor mount towers between the two trucks if not then you will have to find the correct motor mounts (probably highly unlikely aas they didn't make the 391 in the 80's) or fab up some motor mounts.

not impossible but not a straight swap either. another option is to find a decent running 429 or 460 engine as a swap candidate. should be a direct bolt in for the 370 other than the 370 and truck 429 used a different front snout dimension so the accessories might not swap between the 370 and a car 429 or 460. but then you could just use the accessories that come with the swap motor.

rgds
Mike

 

This is a doable swap, as long as your doner engine is complete from bell housing to front motor mount. The trans will bolt to the correct 391 bell, and the 370 and 391 both mount in the front, the 391 exaust will be different. Since you have both trucks this job will be a easy one.

Have A Good Day------Hotwrench