Rear bearing or gear noise?

[gtblast]

I finally got my 70 GT on the road. There is a noise coming from the rear of the car as I ride down the road. I do not hear the noise in first or second gear, if it is there, it is very faint. The noise gets much clearer in third gear and more so in forth gear. However, it is not coming from the transmission, it is coming from the rear area. It is very noisy when accelerating and decelerating, but faint or not there at all when coasting or just between accelerating and decelerating. I am thinking it is either a pinion bearing or gear noise. I had a pinion bearing go out in an old Pontiac years ago, but it made noise at all speeds and all conditions. I have checked the oil level in the rear and it is ok, but I have not tried draining it and refilling it with new oil. Any insight would be greatly apprciated. I have a 71 GT parts car and may just swap the rear out, but I would like to nail this down before I do that.
Fred

[wrench459]

Double check the trans input bgr. Thats were my money is.
Or get to a shop that has a electric ear "It will nail down the problem"

[gtblast]

Originally Posted by wrench459 Double check the trans input bgr. Thats were my money is. Or get to a shop that has a electric ear "It will nail down the problem"

Wrench,

Why would you suspect the input shaft bearing? I am thinking that the input shaft bearing would make noise with engine speed and anytime the clutch is engaged. I am aware that drive train noise can travel up and down the drive train and make it difficult to locate. I pulled the shifter boot out so I could hear the transmission better, but the problem appears to be at the back of the car. The transmission is eaiser to change than the rear and I have a spare, so maybe I will try it first.

[markandson]

Look at the torque tube support and bearing, if it happens under load only there is a good chance that it is your problem.

[gtblast]

Here is an update: I put the car up in the air and with it running at fast idle in 4th gear, I used a broom handle to listen for the noise. I could hear it the loudest right at the pinion bearing area, so I am thinking that is where the problem is. Took a good look at things while I was under there and found the transmission rubber mounts are shot, the torque tube donut is shot, and the two torque tube rubber mounts are shot. So, looks like I have a lot of work to do. I think I will wait a few more weeks for the weather to cool off some and then swap out the rear and replace all the old rubber parts.