KA-thunk

The 3 speed original tranny on the '60 Val winds up pretty high between 1 and 2, 2 and 3, and sort of slams into gear with a ka-thunk. I lessen this by letting off the gas at a lower rate of speed and pausing until the transmission finds the next higher gear, with less noise and jarring.

I don't mind living with it, as I am not interested in rabbit starts. The issue is what am I looking at? Is this just the noises of an old car, or is it a death noise?