What year is the engine? The 216's and splash-oiler 235's have dowel pins in the upper main bearing shells that engage holes in the block, so the crankshaft would have to drop WAY down. The later-model 235's have anti-rotate tabs on the ends of the bearings, and those would be a lot simpler to change. Be sure to get the right size bearings. If they're undesize, the dimension should be stamped on the back of the bearings- - -.010, .020, .030, etc.
Jerry
