Hold on, don't throw it out. I understand you're at the end of your wick, but let us help you. It's tuff on here because not many people use RCTech anymore.
Take the whole front clip off and check rotation, both forward and backwards. Make sure the driveshaft is on the correct side of the chassis brace. There's three lengths of screw. Short for the steering, med for the middle screw and long ones for the front where the bumper is. Also when you put the coupler onto the pinion shaft, don't lunch them together, just let them touch. Too loose will not have a good mesh between ring and pinion for the diff, and too right will bind the bearings.