My '89 has hydraulic mounts. They're rubber donuts/bladders(?) about 4 inches across and maybe 2 inches high filled with clear hyrdraulic fluid. The solid rubber are .... solid rubber and much smaller. The engine should rock back a forth slightly when ideling. If it just sits there the hydraulic mounts are bad and the oil pan is resting on the frame member. Solid rubber mounts usually just break and the engine moves around alot when there's a load put on it during acceleration. Although I've purchased old cars with rubber mounts that have turned to stone due to age which really creates alot of vibration and makes the inside rear view mirror pretty useless.