Re: Will a 1977 lower unit fit a 1978 evenrude 150
Look at the shift rod top. If it has a threaded "barrel" on the 77, it will not exchange as it is a Hydro-mechanical shifted lower.I believe that 78 was the "break-year" for hydro and mech'. 78-early 91 are interchangeable the 86 break was when they switched to a wider cavitation plate, a mostly cosmetic change. In late 91 they switched to a 2 piece driveshaft setup that can be used on earlier units with the proper upper driveshaft. In 93 a change to the crankshafts (sleeved lower seal wear area)goes hand in hand with a change to the driveshaft (shortened by about 3/8")because the crank splines arent as deep. If the 77 is hydro (has threaded barrel on shift rod top) and has a 6 bolt cover where the shift rod comes out of the lower, it is hard to find, and valuable to someone who needs it. (just the fwd gear from these units last sold for over 350.00new!!)