The bearing that goes over the pin is Buick part no 1324831 - there are some available here and there on eBay. The bearing consists of two thin steel sleeves with molded rubber filling the space between the sleeves. OD is 1". ID is 1/2". Length is 1". Steele Rubber Products is making them as part of kit no 1390518. That was a Buick kit no with parts to rebuild everything on the equalizer. However none of the original Buick kits could be located.
The spring is a no 1321676 - those are showing as available on eBay too.
What has been, can be again. (Bob Wills, 1942)