locked differentials

[Sentinel]

Awesome thanks for the info. I've got thick bearing grease in the axles but I think I'll lock my rear rear.
I also think I should change the tires asap as well, the standards are pretty miserable grip-wise, I think that's half my issue.
Is there a standard that people move the 5th wheel forward on the tamiya's? Mine is still centered from stock, what's the scale measurement to move it forward, if 9" forward of center is the 1:1 normal?

sorry for the hijack kaptain Jack.