rug the i/o was the same,,, impeller in lower unit
mboy the $4000 price u said is that dealer or marina price with labor????cause its the labor that kills you,,,thats why i went online and found a super cheap head and did the install myself,,,, the fact i was a car mechanic for 3 years and the i/o is basically a car engine helped a lot,,,
either way it dont matter, u dont change it you get effed,,,so change it when u can