Yes, there are two "Main bearings" one on the input shaft and one on the main shaft. The front bearing is probably a 308 bearing in your case "pun intended" and the rear is a 307. I would like to see how the bearings spin and how they look. If that's the case, cool replace and drive it. I would put a fresh set of gaskets on the side cover and tailshaft while its apart. They are cheap. There are different thicknesses of the 308 bearing, make sure you get the correct one. On the back of the input shaft there are needle bearings where the main shaft mates to it. Have them inspect those to make sure they are in good shape.