Hi everyone!

I've run into a frustrating issue – there's a significant vibration when driving at speed, and it's clear the driveshaft is the culprit. The vibration is worse around 80-90 km/h. Forum discussions suggest it's probably due to imbalance.

I'm trying to choose the best way to resolve this?

Take it off and balance it with specialized equipment. It might be the best solution, but it's inconvenient and pricey. I've heard it can also be balanced while still on the car. They use special equipment to balance it on a lift without removing it.

Has anyone tried balancing their driveshaft this way? Let me know how it worked for you. Thank you in advance!

Before you go too far down that road, (pun intended)
Are you positive that it is not an bad U joint? These things can eat them quickly if you do not lube them regularly.
Lube at every oil change would not be too often......Have you ever changed them?
To check, Get all 4 wheels off the ground and get underneath and check the UJs for play.

What makes you think it is the rear propshaft? Out of balance rear wheels tend to hit resonance around 55-60 mph (88-96kph) and that can be felt through the whole car.

Or front wheels. I agree with the two above. An out of balance drive shaft is possible but U-joints or wheel balance would be far more likely.

Out of balance front wheels can be felt through the steering, but with rear wheels you don't feel a lot through the steering wheel, you feel it through the seat of your pants.

slow down a bit, first thing is go and look at the shafts , there's two of them , if you think its a balance issue and it wasn't there yesterday but is today then it would have thrown a weight off the shaft and you would be able to see where it came off. the next step is see if there is any movement in the uni joint , to really see this you need to remove at least one end to really see if there is any movement . also check that the pinions and the output shafts from the transfer box and the diffs are tight , no movement.
PS my guess is uni joints.