Starting to get worried

[red]

I had the nut that holds the pinion yoke come loose on me and made the rear in my '65 whine.

To tighten it, I had to unbolt the u-joint at the rear end of the drive shaft and tighten the pinion nut inside the yoke. Pinion nut could be turned with my fingers so it was very loose. If your pinion nut does not want to tighten, don't try too hard, because this sets the pinion depth and you don't want to crush the washer in there that is keeping the depth correct.

It could be many other things, oil low or needs to be changed, something broke inside, ect.

I ended up installing a new Currie pig with traction lock and 3:55 gears. Not a cheap solution, but it was something I had been saving for.