Ok so i have a 351M from a 1979 bronco and next week im ordering my engine stuff for it, but my question is this:

Im putting it in my 1994 f150 4x4. I am going to use the bronco motor, 4sp manual transmission, and axles. You can put longtube headers in a 1979 bronco but you cannot put them in a 1994 f150 because they hit the front driveshaft. So if im putting the whole drive-line from the bronco in the f150, i should be able to use longtube headers for a 1979 351M bronco, correct?

 

the only way you can know for sure is to fit them up and see where they are going to exit,the 351m wasn't as option in 94 as you probably know. And you can fit long tubes in a 94 f150,just like i have in my 95 f150 4x4,no problems hitting the driveshaft.

 

Oh really? i was told that my 94 f150 4x4 with a 302 I couldnt have longtubes and i couldnt even find any listed for a 94. ok iguess ill just have to buy some and hope for the best unless anyone else has some input before next week

 

The issue here is how much different in size the 351w/302 and 351m are,and I know absolutely nothing about the 351m,so I can't tell you how close in width/height they might be.

 

351m is the same size as the 400

 

There are issues with longtubes hitting the driveshaft in these trucks when they get a SAS conversion, but that is with longtubes designed to fit a truck with the TTB front axle so that really shouldn't be a surprise to anybody.
As stated the M series was never an option but considering these trucks did get a 460 I doubt there will be any problem making the engine fit, you may have to fab engine hounts however and headers may also be a custom project.

 

How far do your longtubes hang below the frame or do they stay tucked up inside? Im just not sure if i would have to worry about tearing them up off roading. my dad didnt reccomend it said i should go with shortys. I know they hung kinda low on a 302 mustang.

 

mine are tucked up inside the frame.