Odd noises while shifting

So I have a 198 ci slant six in my '70 Dart. I have a TorqueFlite A904 auto transmission as well.

When shifting, usually down-shifting from 2nd to 1st, it makes a low thud. It gets into gear well, but the sound gets annoying.

Another odd noise coming from the transmission is this pinging noise. It sounds like an M1 Garand ejecting a clip after the last round.

I changed the belts, new filters and changed the fluids as soon as I got the car.
The noise startles new passengers and has been an annoyance while driving around town.

Is it the linkage? Or something I don't know about? and has anyone else had these odd sounds?

Thanks in advance.