the B&M specialty flex plate does exactly that same function, not dead on like it would be if you handed the rotating assy and this flexplate & front dampener to your shop for balancing but it duplicates Ma's factory torque converter balance which is so so but adequate. Order one & you are set. the 340 MAY have slightly different front to rear spacing of the block mtr mt lugs on the DR side so it MAY take a different mount. the 360 will have a different dampener and pan & other than that they will be externally the same AFAIK. there are (2) "center" sump 360 pans that I am aware of, a 392 and a 876 (stamped on bottom). the sumps on both are ~8" long and the sump bulge starts 4" back from a vertical plumb line straight down from the very front lip on the 392 and 2" back on the 876. both take different pickups (I can dig up pics if needed). grab your tape & measure the 340 pan before you pull it