about 15 years ago a member discovered a modern Ford permanent magnet gear reduction (PMGR) starter that would work in our 351C Panteras.
Their purchase had been from DB Electrical, an eBay seller that also has their own website:
many owners have purchased a PMGR starter from them in the ensuing years, with good service and good results.
The PMGR starter is stronger, smaller and lighter and is a direct bolt-in, but it does require some slight rewiring of the firewall mounted starter relay. It requires a new wire (#10) from the old firewall starter relay to the relay terminal on the PMGR starter.
NOTE - it is likely the two mounting studs will need to be replaced with longer studs.
IIRC, the original studs were 1/2 SAE and 1/2 metric. YMMV 😉 Those studs aren’t very hard to find, but you could just replace with studs having dual SAE threads. In either case, reduced head nuts (commonly called flange nuts) are advised as the PMGR starter case design intrudes on one stud.
if your studs are metric they are most likely M10 x 1.5. These are available in serrated base and nylon insert versions.
DB part number back in the day was 3223. However, I recently discovered they have updated their part number.
The new DB number for the PMGR starter that will fit our Panteras is 410-14033.
The industry generic number is SFD0012
However, a word of caution is needed.
due to potential differences in flywheel size the starter MAY NOT WORK on cars equipped with a ZF-1 transaxle.