401 bolts in with the right motor mounts, trans bolts right to it.
Life expediency of front and rear axles, less than a week.
My buddy has a 401 in a CJ-5 that he bought new, SOB sounds like a late model dirt track car when he opens it up.
He still runs a built T-150 3-speed, he swears nothing will break in it and changing a trans is easier than a clutch or rear end, I have never seen it break on the trails, and we do some pretty crazy things with jeeps.