Hydrostat Noise

I have a question on locating a horrible noise in my final drive. My Scat Trak 1350 is up and running but I'm getting this deafening noise when I try to turn left or right. If I slowly more forward or back in unison the noise is a lot less noticeable but if I turn OMG! I checked the final drive oil in both the left and right compartments and they are full. Keep in mind the oil resembles that of chocolate milk more then 10W30. When I had the rims off I checked the axels for slop but didn't notice any. Can I have worn out axel bearings or the idler bearings? I'm thinking of wearing ear plugs it's that bad! I've parked it and was thinking of jacking the entire machine off the ground and running the wheels with no load to see if that would make the problem go away. If anyone can help me I'd appreciate it. My machine was made by Thomas as a T-133 but sold under the Kohlring Scat Trak 1350 moniker. Also if anyone has ever done a conversion from the original pin on old style quick tach system to the new universal quick attach system I'd like to get some info on that. I'm guessing I can get a pin on system but unsure of where I should look and what size this machine would take. Thanks in advance!

I'm doing some reading on pre-loading of the axel bearings. When I replaced the rims on my machine I did notice a slight lateral push pull movement in the wheel hub during the pulling of the rim and after when I simply tugged on the axel hub. I'm guessing this is the issue that pre-loading resolves. My service manual says the pre-load should be set to 0 on the axels. So that means tighten the axel nut till the moment that lateral movement disappears right? Any more and the pre-load will become to severe and can cause the bearings to fail right? Maybe someone can conform or deny my suspicions.