Leo, OK, they are called end connectors, that fit over the bars sticking out the ends of the track blocks, connecting the two blocks, and the bolt that holds them in place is a wedge bolt, (and nut) from it's shape, that fits in a flat space on the track block's bars, forcing a bend in the block as it rounds the idler/sprocket. That's what gives the track the "live track" designation. Don't know if the model is set up like that but I doubt it. The guide tooth is a center guide.

Bill