I have some play in the rear end. The only way I can describe it is I had my '86 Z on jack stands and just had the U-joints replaced. I put the car in neutral to rotate the driveshaft so I could clamp down the other half of the joints to the yoke coming out of the diff and noticed the tires turned about 3 inches before they caught the driveshaft and turned it. I thought maybe it was because the other side wasn't bolted down. After bolting it down, I still have the play. I take this as a sign of worn out gears but not sure if it is the axle or ring and pinion. I don't know for sure. Any suggestions?

I also have a problem with the car shaking throughout the driving range. I have upgraded from a 305 TPI to a '76 Reman 350/350, 4 bolt main, with 30lb. injectors, removed cam it came with and put in a CompCam 239 grind, FlowTech Headers, High FLo Cat, 3 inch exhaust , and Performance 80 Series muffler. I am running on a rebuilt 700R4 Tranny, new 350 flywheel but a stock torque convertor. Stock 305/350 Internal balanced Harmonic Balancer and accessories. No A/C or Smog pump or pipes. I know most of the parts in this other than what I have changed are stock since I've had it 10 years of 16 and alot are wearing out. Just looking for anyone with same probs and/or experience and/or suggestions?!?!?

 

The play in your gears is normal. 3 inches seems excessive, but the largeness of the wheels (compared to the size of the pinion gear) exaggerates this normal condition called "backlash". The only accurate way to measure the backlash is the remove the diff cover and measure it at the ring gear w/ a dial indicator.

As for the vibration, get the vehicle to where its vibrating good and put it in nuetral. If its still there, its probably driveline related. If its gone, it may be an engine/torque converter vibration.