i bought a 1980 check mate with a 300 hp o/b and a spair motor for parts. both lower units were off when i bought it.one had a crack,one looked good.i can't find parts any where.i don't know much about boats except they are expensive to fix.i took it to get it looked a,they told me both lower units were bad and they cant fix them,then charged me 100.00,to tell me what i knew.what should it cost to rebuild one.or any other ideas?????<br />thanks.doug