'74 85 hp merc LU compatibilty with '79 80 hp merc

[shawnbradley]

I've run into issue with my '79 80 hp merc LU. Probably needs dog clutch and seals. I would rattle in reverse and now jumping out of forward. Long story short, I found a LU for a '74 85 hp merc for $100.00. Owner says seals good shifts great. Can I swap the lower units?
Thanks,
Shawn

 

[jimmbo]

Should swap, the Gear Ratio for both years was 2.3:1. The 74 unit will look a little less Sleek