Forged steel or cast crank???

Mopar 340 V-8 Engine - Carburetors and Cranks
1968-70 - AVS
1971-73 - Thermoquad
1968-1971: forged crank, part number 2532457, 2128869, or 2843868; service part number, 2843868
1972-73: cast crank, 3462387, 3658393, or 3751841 (some 1974-86 cast cranks use the same 3462387 casting number as the 1973 340 crank); service part number 3751162
Chronology of the Mopar 340 V-8 engine (Stephen Havens and Michael Volkmann)
1968 - 340 released, rated at 275 horsepower, with:
forged crank
four-barrel Carter AVS carburetor
hydraulic cam (a more aggressive cam was used in the four-speed cars in 1968)
unique “X” casting cylinder heads, with 2.02” intake, 1.88” exhaust valves
10.5:1 compression ratio
dual plane intake (the 318 had a single-plane manifold with a two barrel carburetor).
1969 - Unchanged, except manual transmission 340 engines also had the (formerly) automatic-transmission camshaft.
1970 - Two distinct versions of the 340 high performance engine were made. The four-barrel carried over without changes, while a new Trans Am (T/A) version, dubbed Six-Pack on Dodge and 6-Barrel on Plymouth, debuted. This 1970-only 340 had:
three two-barrel Holley carburetors
“J” casting cylinder heads were unique to the T/A, with unique pushrod holes to allow for oversized porting on the intake runners
a unique rocker arm/shaft/pushrod assembly
thicker webs in the pan rail and other areas
the ability to install 4-bolt mains on 2 3 and 4
1971 - The 340 four-barrel remained; the triple-carburetor version did not.
Advertised compression dropped to 10.25:1 but horsepower remained at 275 (gross)
Carter Thermoquad carburetor was used
340/360 “J” casting cylinder heads with 2.02 intake and 1.88 exhaust valves (not the same as the T/A J heads)
1972 - The 340 four-barrel dropped to 240 horsepower:
Compression dropped to 8.5:1; the compression height of the piston via wrist pin location changed by 0.10”
The crankshaft was switched from forged to cast somewhere in the production cycle, believed to be in early April 1972, with engine 39118000 (thanks, Karl Thomas); a milder camshaft was used
340/360 were moved to “J” casting heads with 1.92” intake valves; exhaust valves remained the same
Paint went from orange to corporate blue
1973 - The cast crank had a different number than the 1972 counterpart, because it was shot-peened for greater strength.
1974 - The 340 did not re-appear for 1974, ending an era. Instead, the 360 four-barrel (E58) was provided, with the 1973-340 cam, carb, and intake.