Don -
I took a bare casting 348, bolted on a pair of clam shell mounts from a sbc, and tried to set it on the motor mounts: the holes on one side almost lined up (clam shell mount was 1/2" too high over the motor mount), whereas the other clam shell was 1" too high and 1/2" too wide for its motor mount. To me, it suggests the mounting bosses on the side of the engine are wider than on a small block Chevy.
I will research if a clam shell mount was ever made for a W motor and let you know.
Tim
