My car has been making more and more noise until it was obvious I needed a pro

A faint ting noise began in cadence with the drive shaft revolutions, and increasingly became louder over several days until it became very obvious that there was a major problem. There was never a problem with the car prior to this issue.

Initially I blamed the transfer case, as the noise seemed to be coming from there, but after trying another transfer case with no change in the noise, I pulled the transfer case, jacked the car off the ground, put it on stands, started the engine and put it in gear, crawled under and watched the transmission output shaft rotation.

To my surprise, the output shaft was not turning symmetrical, and it was obvious and not difficult to spot immediately. I turned off the engine to check the output splines. The splines were chewed, so it looks like the faint "ting" noise was when the splines were first not quite meshing correctly with the drive shaft splines. As the splines increasingly got chewed, the noise increased until a problem was obvious.

Transmission mount and engine to transmission bolts were double checked. There is no adjustment possible, so alignment seems not to be a possible factor.

I pulled the transmission and got another one from a junk yard. Installed it and took it for a test drive. I couldn’t have expected better. It ran and shifted as smooth as silk- for two days, when the faint “ting” noise could once again be heard. It sits this way today. The second transmission
also had high miles.

The transmission involved is the 42RE, similar if not identical to the Chrysler A-500.