Can anyone tell me if the lower unit from a 1954 7.5hp (model 7514) motor would be directly interchangeable with the l.u. on a l957 5.5 (model 5514)? I found one at a local junk store but I don't want to try & talk them out of it unless I know it will fit. I'd like to have a spare l.u. for my old 5.5 Fisherman. Thanks.