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1963 merc 650 lower unit interchange

I swapped out my L/U on my '77 500 Thunderbolt, you need the shaft length, the number of splines, and whether it has a preload pin on the top of the shaft or not. The best way to compare it is to start with the casting number. The casting number is up inside the L/U in front of the water pump, it will be a number like 1643-6037. Most used parts sellers can help you with a swap out based on that number.
 
When I was looking I checked out Ebay. Many of the sellers are used parts dealers and will be able to tell you if it will fit. You'll be suprised how many will be there.

I hit it lucky, a guy had a lower unit advertised on Ebay and I contacted him with my info asking if it would fit. He replied back to me saying that the one advertised would not fit but he had the right one for me. The unit was used but pressure tested and included a new-looking prop. He told me to bid on that unit knowing that it was wrong, if I win the auction drop him a note saying that we spoke and he would send me the right one. Apparently the one that he had advertised was a bastard unit and no one else bid on it. I won the bid for $100 with $45 shipping and it fit and works perfectly!

If you just needed a housing, your exact model is on Ebay right now:
http://motors.shop.ebay.com/eBay-Mo...Accessories_Gear&_trksid=p3286.c0.m282&_rdc=1
 
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Wow!!! That's a stroke of luck. Thanks for the closing mention as it educated me on how this could be handled (I'm sure it will help others too.).

Floyd
 
Remember, there will be parts and labor involved in swapping everything over, that is just a case. If you're like me, a seal went bad and it injested water when the former owner had it. The water froze while stored for the winter and cracked the case near the prop.

Upstate NY.... I vacationed/fished at Loon Lake in the Adirondaks, anywhere near you? I'd go back there in a second, beautiful place!
 
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wow hotrod ,you explained exactly what I am looking at. previous owner did not maintain and water froze while stored for the winter and cracked the case near the prop.

I have a few lines on one but it is not an easy find.
 
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