Hey guys my car never used to but when i hit around 150 - 160kph
I get this extreme vibration through my car & driveline.

I recently put a ED Diff & tailshaft into my EA
& Got a new set of tyres.

I'm thinking my rear tyres need to be balanced?
But could this have anything to do with the ED diff Tailshaft?

Thanks Wez

Did you line up the yellow dots at both ends of the drive shaft? These dots represent the lighter side of the shaft after balancing. Once lined up to the heavier side of the diff and trans the driveline should almost have a 0 imbalance. If the shaft is a 3" steel isnt is recomended doing speeds like that especially on public roads as its illegal apart from parts of N.T. Driveshafts made for the E series XR's and GT's being sent to N.T were a 3 1/4" alloy with a carbon fibre wrap to withstand the open speed limits there.
All you can really do is have the U.J's checked/replaced then checked for runout and re-balanced.