Volvo 280 Question

[problemchild]

I've been looking for used 280's and noticed that some 'drives route thier exhaust through the back of the cavitation plate, While others do out the bottom. Is thier any difference, or anything I should know before buying one,
Thanks again,
-Problem Child

[BigGrizzly]

The 280 go out the ventilation plate I like mine but i hav e through hull.