Are you looking to identify the engine or swap a flywheel? You cannot use a internal balcnce flywheel on an external balance engine (and visa versa) without rebalancing the rotating assy. The FT forged crankshafts have the larger snout. It's either a 361 or 391 crank. Possibly an odd 389 even. These were forged steel cranks and the 391 cranks are worth a good penny. If your looking to identify the engine post the crank and rod numbers. Block and heads also. If it's a 391 FT engine the block might be pretty good and maybe a 4.13 bore candidate if wall core thickness checks out. G.