Installing $100 DCC W/Sound on a 1$ 1980s Tyco Locomotive - Will it Work?

A common question I've been asked is weather or not you can install digital command control on older ho locomotives from the 80s. It's certainly possible but what level of difficulty is required to do so and is it worth it?
I decided to try it out myself and install a decoder in this 1980 Tyco golden eagle locomotive. I ended up having to do some small repairs along the way but otherwise the install went pretty smooth.
Some CV changes were made to the decoder to improve the sound and set the correct road address to the locomotive. After that it was a matter of just running it like any other digital locomotive with the Dcc throttle.