chrysler lower unit compatibilty

dutch420

Petty Officer 3rd Class
Joined
Sep 16, 2012
Messages
84
Hey guys not sure if this one has been covered yet but i figure we would all like to know.. i was wondering what the compatibilty is with chrysler lower units.... Ie year and hp.... I my self have a 73 85hp chrysler. And may be needing to swap or rebuild lowers. So i fogured i would look for a used one but am kinda lost as to what my choices are.. I know there is at least a couple diff styles. But not sure what i can choose from. Any ideas for me .... Or any info on what u can use for the motors from diff years and hp..... Thanks guys....this is my lower
 

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Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
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Re: chrysler lower unit compatibilty

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That is the old 2 piece lower unit with a splined propshaft and thrust pin prop. It was used in two styles up to 1977 or 78. You can use almost any lower unit from any 3 or 4 cylinder engine up to that year. The earlier lower unit was a little less streamlined. While the casting looks different, it will still bolt up to your midleg. in those years, the only 2 to 1 ratio lower unit was the 90 horsepower engine. This ratio will wake up your engine and is good for a couple of MPH more with a prop pitch change--go up 2 pitches.

Later 2 piece lowers like yours are three bolt, meaning that three studs pass up from the gearcase and secure it to the upper portion of the unit. Earlier lowers were 2 bolt. Obviously less strong but still well able to handle anything your engine can deliver.

Props for the 2 piece are becoming difficult to find and no longer can be re-hubbed. They do come up occasionally on ebay BUT tend to be expensive.

If you want to put in a couple of hours over the winter, you can change the midleg and lower unit to the newer one piece. Everything else will remain the same. This is worth 3 MPH more and you have a much better selection of props.

The two piece lower is NOT swappable with the one piece lower. The midleg and driveshaft is one inch longer on the two piece.
 

dutch420

Petty Officer 3rd Class
Joined
Sep 16, 2012
Messages
84
Re: chrysler lower unit compatibilty

Ok great info frank. Me and others in this situation could really use this info..


Now if i upgrade to the one piece lower which sounds like a great idea is force parts an option.? and if so is there a year range? Is through hub exhaust an option? And is there a certain gasket/seal kit i would need.

Thanks again for the info and help
 
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