Alright now dont hate me but ive seen some sites showing people dropping newer mopar hemis into old kbodies, but im wondering how much easier/ difficult it is to put a 5.7 magnum hemi into an m body? An 84 5th avenue.

 

Sounds like a tight fit !!

 

Its basically a funky small block so I don't know what the problem is, fab mounts to use the transmission on the 5.7 you will need to make room for it possibly you could use a floor pan from a Challenger for clearance. It can be done it's just how much time and money do you want to spend.

An M body is a later F body which will take a RB motor or even a gen 2 Hemi so a gen 3 is an easy fit size wise.