I did the Nova swap (new everything, 30 spline Yukon axles an eaton posi and 3.42 gears--good pattern). Now I have a whine at the same speed (about 45 mph) in third gear (TH 350). It starts abruptly and if I let off the gas the sound declines. I've tried to figure out what might be going on but with no luck. The pinion angle is ok, new U-joints-- not overtightened, the drive shaft was shortened and balanced (maybe a .25 inch too short looking at it now). Do you have any suggestions?

thanks,

what was the backlash,and it does have posi lube right ?

Yes, it has the right lube (not GM though). I'm not sure about the backlash.

Thanks,