I'm doing a driveshaft swap from a Crown Vic Police Interceptor to a Mercury Grand Marquis. Ditching the civilian steel shaft for the police aluminum shaft. This is a common swap in the Crown Vic community, but nobody ever mentions a re-balance.
In order to do this, you need to re-use the civilian yoke and put it onto the police shaft, keep the police u-joint at the differential and then add a spacer at the differential end. The reason for this is the police transmission tail is about 3/4" longer roughly making the police driveshaft that much shorter; hence the spacer and the civilian yoke has splines that go all the way to the end to match the civilian trans tail.
Does the entire assembly (civ yoke and police shaft) require a re-balance or will the change in yoke make no real difference?
I would just take a chance and assemble it. The shaft should already be balanced. On the small chance that the adapter vibrates, it's not that hard to take it back out.
