This may seem somewhat oversimplified, but most - not all, grant you - of the american four speeds of the "muscle car era" are quite similar in their design basics. Things you will need to have on hand, besides a good exploded drawing, and if you can find one, a shop manual at best, or a Chilton's or Motor's, or perhaps a Hayne's (all three would be golden) covering the year of your tranny, are a large pan or tray that is big enough to catch parts when they come tumbling out of the case during disassembly, snap ring pliers, some various picks, and one thing a lot of folks don't think about anymore: some stiff cup grease. Another thing that is handy is some means of standing the trans on it's nose, input shaft down. The grease is for setting the many uncaged roller and/or needle bearings during reassembly in these trannys; the most frustrating ones for me are the ones in the input shaft where the output mates into it, and the needles in the cluster gear. Take your time, quit and take a break when things get frustating, and pay really close attention during disassembly; sometimes something will come apart hard, and little needle bearings come falling out from who knows where - well at least that's the way it will seem. They are really a very simple machine, but to a first timer, they can be very daunting. If you start taking the side cover apart be very careful about detent balls and springs in the shift shafts; they can come flying out and will just disappear and frustrate the he&& out of you.

The noise and damage you describe would point me to a sliding gear, or the cluster gear, and the loose stuff says definitely "take it apart, and rebuild it".

Good luck; I know you can do it.