- The 1968-1978 429/460 engines are internally balanced. The 1968-1978 internally balanced engines use crankshafts that are marked as 2Y, 2YA, 2YAB, or 2YABC.
- The 1979 and later 460 engines are externally balanced. The 1979-up externally balanced 460 engines all used D9TE-AB cylinder blocks. The 1979 and later externally balanced engines use crankshafts that are marked as 3Y, 3YA, or 3YAB.
Clearly, you are trying to install an internal balance 2YAB crank into an external balance applicable D9TE-AB block which accepts only 3Y series crankshafts.
Exchange the crankshaft for a 3Y series 1979 and later crank.
p.s.: For more reading on block/crankshaft differences, click HERE.