My "New" Mustang

[Shaggy]

First off do your heads look like big block Chevy heads if they do you have the C/M/boss heads Several things to look for on your heads on the top front there is a corner that stick out a little past the valve cover your heads will have a 4 cast there if they are 4-V heads. Look between your water pump and block if the timing cover is aluminum and about 1 1/2" thick you have the heads on a Windsor block if the timing cover is a 1/4" piece of plate you have the C/M block. Now the C block uses small block motor mounts and bellhousing . The M uses big block motor mounts and bellhousing. On the windsors look at the timing cover upper right where the water passage is there is a machined surface from that machined surface if the distance from the bottom of the head is about 1" then you have the 351W block if it right on top of it then you have the 289/302W block. All that said if my memory serves me right the FMX only had the small block bellhousing so don't worry about the M series block. The FMX was an iron case intermediate strength tranny the C-4 being the weak pass. car the FMX being in most small block hot rods and the C-6 being the strong truck tranny. (The tranny info is stock strengths the C-4 can be built to be much stronger than the FMX.)