I have been trying to troubleshoot a grr sound coming from what I thought was my front driveshaft, but still have not found the culprit. The grrr started after I took apart both my front and rear driveshafts to clean and repack fresh grease in the inner splines. I then installed new toyota U-joints in both driveshafts.. Well, after installing everything back together and taking out for a test drive, I started to get a grr sound from 65-70mph only. The noise was coming from the front end, so right away I took the front driveshaft off and took it to a driveshaft shop to get it fully balanced and make sure everything was put back together correctly. I drove the car for about 1 week with the driveshaft off, and the grr noise was completely gone... Eureka! I knew I had found the problem. Wrong! After getting the DS back from the shop, I noticed that the driveshaft was installed in phase instead of out phase like everyone here says the front DS should be installed. The guy in the shop told me that DS is ready to run, completely balanced. So I installed the DS back in the truck, and the grrr is back again... Now I am thinking 2 things, either the grr is back because the front DS was put back (by shop)-in phase, or the rear driveshaft is the one that needs to be balanced and checked..? What do you guys think? I am going to pull the rear driveshaft out tomorrow and drive to see if the grrr is gone.... Anyone have any advice, maybe take the front DS apart and install back out phase?