question about thrust washer on 1996 88SPL

[mikeb159]

I recently purchased a 1987 Boston Whaler Montauk 17 with a 1996 Johnson 88SPL engine with aluminum prop. I also got a stainless prop in the deal. Have finally gotten around to changing from the aluminum prop to the stainless one, but have a question: I removed the prop and thrust washer, but when I re-install the thrust washer with the s/s prop, the hub does not appear to rest as close to the lower unit as the aluminum prop hub does. If I leave off the thrust washer, the s/s prop seems to fit perfectly. Is the thrust washer required?