360 engine vibration

Hi Guys, back from our USA holiday 1500 miles around California and Nevada. Awesome country I must say! Anyway whilst there picked up a B&M flex plate and a new transmission mount. However I also have a diff oil leak so stripped that out thinking it was a 8 3/4 dodge item,( bought gasket ready) turns out to be a 9" ford unit???WTF!! and not sure if the prop is also too tight as there was zero movement to slide the yoke into the 727 trans? So starting at the rear I will sort this first, check prop length, yoke play and then move back the the vibration issue.