Whats the Differance??

Ok what is the the differance between a 6 cycl k- frame and V-8 k frame. I have a 6 and its got the U type motors mounts. I do have a V-8 k-frame and it looks the same. is there a differance in with width? I'm looking at using Schumachers.

The K frame is in a 72 duster was a 6 looking to put a v-8. I have used schumachers before when i did my 67 dart went from 6 to 8.