What leaf packs were on the common F or M? I count 4 on my f coupe, but there is a set in my shed with 7? I think. I don't know if they truly were from an FMJ, but the measurements check out correctly.
5 leaf are heavy duty, 4 leaf are standard. The 6 and 7 leaf units are custom, and were available from a couple of catalogs back in the day. F, J and M bodies have the same suspension parts front and rear.