first pic shows how a B&M 340 and 360 flex plate differ.
second pic shows the 340 harmonic balancer for an externally balanced block. This balancer is different than the 360 balancer shown on the blue engine below
this is a neutral or zero balanced torque converter. Basically its just a stock converter for the 904 transmission. You can use this on either the 340 or the 360 as long as you have used both the correct specially balanced Flex plate and the harmonic balancer specific to your engine.
4th pic 360 harmonic balancer is different than the 340s
