There's a possibility that when I reinstalled the drive shaft on my 240 that I misaligned it to a previous mark on the rear pinion flange. Could this be contributing to the vibration that was discussed in my previous post? I noticed that the vibration has become more apparent between 45-65mph since the temperature has dropped below freezing lately.
I have read in the FAQ section on drive shaft alignment and on other sites that you are supposed to mark the drive shaft and the rear pinion flange before removing the drive shaft. Apparently, the front transmission and pinion flange are also included in the drive shaft dynamic balance. Wouldn't this become a problem if sone was to replace the axle using their original drive shaft?
Following this argument, if one were to replace the rear axle, either they would have to use their original rear pinion flange or obtain the entire drive shaft, including the front transmission flanges from the same axle as well.
Before moving to replacing engine-transmission mounts and rear tail housing bushings, I thought I would ask for this opinion since this is definitely a cheaper but very aggravating trial by error fix.