I have an 1987 Johnson 88SPL (ID# J88MSLCUS) and a 1981 Johnson 140 (ID# J140TLCIM) so they both have a 20" long shaft ("L" in their ID#). Does anyone know if the lower units are interchangeable? I ask because the block on the 88HP has an irrepairable water leak but the 88HP appears so similar to the 140HP (power packs, flywheel, lower unit, etc.) that I want to keep it (the 88HP) for spare parts for the 140HP IF they use/can use the same parts. (Particularly the lower unit since it would be a fairly costly repair if the 140 ever needed a new lower unit). Any information on interchangeability/compatibility of parts between these two engines would be greatly appreciated.