I had a 73 Dart Sport 340. I had the engine rebuilt to 70 specs; steel crank replaced the cast iron one. The only issue I had was I had to replace the harmonic balancer and the timing chain cover. The late 340s had its top dead center mark on the timing chain cover on the driver side, where the early 340s had it on the passenger side. I also installed a Comp Cams 292, a 3500 stall Turbo Action converter and 4.56 Sure-Grip unit. That was one nice car to drive. It had a detuned 340, similar to the engine I had in my 69 GTS, and it had an automatic transmission compared to the four speed that I had in the 69. The 69 was a lot of fun to drive, but it wasn't very streetable.