FLM18750 ultimate hybrid bulk

[MAYHEM6969]

Ok could someone help me with a little problem i installed the flm chassis and ultimate diffs and it is a little uncontrollable im running 23 pinion and 68 spur it wants to spin out of control under full throttle i adjusted the shocks no difference i adjusted the slipper no difference i toed in the rear tires a little more no difference im thinking maybe i have too thick of diff fluid im running 50,000 weight do you think thats to thick and locking up the rear end? any help would be apprieciated