Technical Need some help diagnosing unusual sound ,

Trying to help a friend out. he has a 1930 model a pickup truck. It makes kind of a howling grinding sound when you decelerate, especially when your in 3rd gear and are going 25 to 30 mph. doesnt seem to be coming directly from the transmission , or the engine, but we cant seem to pinpoint where its coming from, or what the problem is. Can anybody shed some light on possibilities?
thanks in advance, david

 

U Joints?

 

Howling, grinding, growling are sounds that bad wheel bearings make.

 

Yep, U joint.

 

Rear end gears whining?

 

Since you didn't state stock or otherwise should go off of a stock 1930 driveline ?

Noise on deceleration is usually a pinion bearing.

Put it up in the air and run it, that may help you track it down. At least you can have a shot at finding it.