Is it normal for a 225 to...

I'll try 2 guesses. What is the prize?

1. Sheet-metal tranny inspection plate is hitting torque converter. Happened to me in 1986 after hitting a rock on a gravel road in my 69 Dart 225 w/ 904. A few miles before, I ran across a Scout Master removing the inspection plate on his Valiant 225 which had hit a rock with the same result. Been driving near Wrightwood, CA lately?

2. Noise is actually coming from your radio speakers from ignition pickup, due to a failing coil capacitor.

I doubt the U-joint since in my Dart I think it was bad for 10 years. I assumed the big clunk from P to R was normal. Finally got so bad it caused a vibration at 55 mph. Took it out and found no needle bearings and lots of rust.