1984 t-5 trans qustion

Which 84 T-5 do you have? Is there a tag on the side?

Either way, the transmission makes no difference here. The flywheel imbalance is tied to the motor, not the transmission. So the explorer 5.0 uses 50oz and that's what you need. The 50oz uses a 10.5" clutch. You should use a 1986 (E6) bellhousing for the 10.5" clutch (the 1983-1985 E3 bellhousings could have some issues with clearance since they came with 10" clutches). As long as the input shaft is a 10-spline shaft of the correct lenght, you should be good.

Which leads me back to the trans identification.