72 340 disassemble

I'm curious is this a four-speed car or automatic?I have read that the existing Forged steel crankshafts were put into four speed cars as they use them up at the end of The run before going to cast cranks.
My original 340 Duster was a 3 speed manual '72. It came with a cast crank. Could the forged cranks have been restricted to 4-speed only and not all manual trans?