Technical Need help with '62 Impala SS bucket seat tracks

I was trying to install the drivers side track and noticed that parts had somehow "fell" out. What I have is what appears to be a retainer and a flat-sided roller that fits in the retainer (?) and two small ball bearings about 3/8" diameter. Where do they go in the track?

 

If I remember correctly, the ball bearings ride in a horizontal channel on the sides of the tracks and the flat faced roller rides in the center of the two tracks to support them vertically. I hope this didn't confuse you too much.

 

For a visual, look closely at the in-ards of the other seat track.

 

Here's a pick of a 56 bench seat track, yours should be the same, if not very similar. The balls and roller are captured in the stamped tin retainer.

 

Thanks everyone! Good info!