350 CHANGE OUT FROM 305

[76GMC1500]

They should fit. Both motors are internally balanced. If you see any counterweighting on the flywheel or damper, it is for an external balanced motor and won't fit. The 305 and 350 flywheels may have different numbers of teeth, 153 and 168 are common sizes. 168 was older 350s. 153 covered both the 305 and some newer 350's. Both will work, but the starters have different mounts depending on the flywheel. As long as you use the starer that came off the 305, you should be fine.