1972 mercury 50 hp lower unit

[JSaw]

I've been working on this 1972 50hp mercury trying to install a lower unit on. it is not the original unit off of the motor. but did have white out on it saying it was the same year. The problem i'm having is that the unit is not lining up with the bolt pattern on the two front bolts. First i thought maybe the bolts was bent so put new ones in. Still the same thing bolts aren.t lining up. I drilled the midsection holes now the alighning pen on the unit does not to be lining up. When i went to epc there is 2 part#'s for short shaft and 2 for long shaft. I am asuming that this is a short shaft unit but when I see the 2 #'s for the short shaft I'm asuming that there was some difference in the 2 units bolt pattern.<br /> If any one can help me with this it would be greatly appreciated. What is the differences between the 2 part #'s on the short shaft units?<br /> <br /> Thank You!<br /> JSaw

 

[The Marine Doctor]

Re: 1972 mercury 50 hp lower unit

That gearcase will not work on that engine. We have run into this before at our shop.<br /><br />TMD

 

[JSaw]

Re: 1972 mercury 50 hp lower unit

Can i make it work if I modify it by removing the allignment pen? I've done some looking into epc and the units are real similar inside different water pump kits different driveshaft part#'s and differentreverse part#'s but all of the other stuff has the same part# The forward clutch carrier and prop shaft all have the same part#'s So do i try to modify it or do I get a different unit? <br /> Thanks for your help!<br /> JSaw