A dual exhaust LU will fit and work if it is a Force LU.
Later in 1995-96 they changed LU to a Mercury style..
85Hp was built until 1989 and in 1990 it became 90 Hp with larger displacement.
I think the 90Hp had 2 piece drive shaft, the 85Hp did not.
Maybe jerryjerry can confirm if that is right.