The Fontana-Madden "Cleavor" is indeed a hybrid aluminum block. It uses a custom nose section & water pump similar to the 351W and oiling sourced from the Windsor, but accepts the 351C main bearing sizes of 2.75". It is very popular with the dirt track guys, usually being sized at 410 or 440 cubic inches using custom steel cranks. It accepts vast overbores and usually wears aluminum stagger-valve heads, racing intakes & headers. Be aware that this is a pure racing engine and is used to make money going fast. Virtually nothing you now own will fit this motor, & if it's complete, you'll have to throw away the headers, flywheel & clutch, and since many run dry-sump oilng, this will present its own problems. So it will cost you dearly to set one in your Pantera- I'd estimate a low-ball $15,000, suitably detuned from the usual 850+ reliable horses the dirt guys run. Once in a while you find a used one thats being sold at a swap meet or E-Bay 'cause someone's getting out of racing or because its been blown up so often, the team doesn't rust it any more. Virtually any damage in an aluminum block can be welded, but there's a point...One Pantera guy I know spent 3 yrs running a repaired Cleavor that had had 4 of the lifter bosses blown off & repaired. He lost 3 cranks, finally concluding that 'something' wasn't quite right inside the block, so he sold it and bought a brand new one. Magically, no more oiling problems. Be careful with bargains- some aren't!
