I too think it is a 383 forged crank. Here is the 400 cast crank balancer.
Also the 383 cast crank was with 2-bbl and auto tranny and has the same style balancer as the 400 CC balancer.

Balancer 400.jpg
72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
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