Slow, Driving Rustoration 1972 Dart

Story 2 from this weekend.

So I got the starter on and decided to go to Autozone and finally get the transmission filter kit and oil change stuff. Filled with happiness with the non-flooding and easy starting car I was ready for some routine maintenance. I spent way too long in the ATF section looking up suggestions on the interwebz for what fluid I needed. I got the stuff and headed home.

Again, I got less than half a block from my house, turned the corner and BAM! The car stopped dead in its tracks. I was only going about 10 MPH so it wasn't to scary but, I was of course concerned. My first thought was my hack job of a muffled had fallen off and stopped me, then I thought maybe drive shaft. But after it stopped me, I was able to drive again, for about 10 feet then BAM! Something locked up again. This time I could tell it was the left front tire not moving. I had just rebuilt all four brakes, hardware and all, so I thought maybe a spring had come off and a brake shoe was flopping around.

I was able to back up, then I could pull forward about 3 feet before it would lock up again. So I decided to back into my driveway. Then it switched, I could go about 2 feet in reverse then it would lock up. Evenutally it just stopped being able to go at all in reverse and only a few feet in drive. I was able to drag the front tire into the driveway and I had to go to work at the restaurant from the evening.

Now I had the brakes completely disassembled so I assumed I did something wrong. I had even taken the backing plate off to clean and paint it so there were many things it could be. I thought about it all night assuming it was the brakes.

This morning, Sunday I got up early and fixed it in about 6 minutes. The only tools I used were as follows:
Lug wrench, jack, jack stand, and needle nose pliers.

The drum was really hard to get off but not locked up hard. When I got the drum came off something fell out, that fixed the problem and I put it all back together and it was fine.

Can anyone guess what it was. There was a hint in the story above.