There are no bearings, per se, on the Ericson 30 rudder assembly. There are two bushings. One is the tiller assembly piece, at athe top of rudder assembly and installed in your cockpit floor. Unless its been replaced, it would be bronze. The other is a two piece shoe that fits over the sked that supports the top of the rudder. Those pieces would be bronze also. They actually bolt together with bolts running through the fiberglass skeg.
The tiller assembly should be easy to check for. And, if your boat is out of the water, just take a look at the skeg to see if the shoe pieces are there. If your boat is in the water, you're going to have to have it hauled anyway to install the rudder.
Which boat did you end up with? The one with the grey non-skid, black canvas, and nice britework? The one out on the buoy (think it had a navy hull)?