Where the "arms" go into the track, one of the plastic "nuts" that goes over the little metal ball joint broke. It probably cost a penny to make, and the dealer says they don't carry them. Do I have to go to a junkyard, or can anyone steer me in the right direction to getting this cheap fix done?

'97 Dakota, 3.9 L 6 cylinder, 4WD with bench back seat

Thanks!