Ford used various different bolt patterns. I think it makes sense to have your front and rear rims and bolts match.
There are three things that need to match:
1: The number of bolts (probably 5 on the M-II)
2: Bolt circle diameter- 5", 4 3/4", 4 1/2"...
3: Bolt size- 1/2", 7/16"...
For a Chevy rear differential you might find "5 on 5" with 1/2 bolts or 5 on 4 3/4 with 7/16 bolts, etc...
It took me alot of work to find a rear differential of the right width with the right bolt pattern and gear ratio, and I think it was worth it!
Width was the hardest part, after that the other stuff is easier to change. To figure out the width I needed I figured out the tires I wanted to use, then the minimum width rim they required, then got the rims and figured out what the difference in backspacing was from the inside edge of the stock rim to the mount plate on the stock rims compared to the new rims and discovered I needed 1 1/2 inches more on either side of the axel and ended up with an axel 3" wider than my stock one. The main difference was the backspacing.
best of luck!
