Early '72s were forged crank and used the internal balance balancer. . . . Late '72s went to an externally balanced cast crank (and lower compression and smaller 1.88 vs 2.02 valves) and used the "cast crank 340 only"
I have no idea what the rules were supposed to be re cast/forged crank in 72 340s (and I'm not sure they were consistently followed anyway), but the first 340 I put in my 65 Barracuda back in 1973 came out of a wrecked 72 Charger. It had a forged crank, with 8.5 pistons and the small 1.88 intake valves. Balancer was the neutral-balance forged crank unit.
I never saw the Charger; my Dad bought its motor while I was on a destroyer off the coast of Viet Nam. My understanding was it was an automatic car, but the crank was machined for a pilot bushing, so it may have been a 4-speed (or 3-speed manual). Whether the transmission made any difference on which crank a 340 got that year, I have no idea about that, either.
