Quick question- Replace 1969 MC-1 with 1981 Alpha?

[Starcraft Enterprise]

I broke the lower driveshaft on my 1969 MC-1 120. Found a good deal on a 1981 Alpha 120. I am 99% sure this will bolt in place without replacing my transom ring. Am I correct? What about the driveshafts, the same?
I am hoping to check my alignment, replace impeller, bolt in on, change the oil and go boating.

 

[Bondo]

Re: Quick question- Replace 1969 MC-1 with 1981 Alpha?

Ayuh,... The housing should fit, but ya need to use yer old, shorter drive shaft...

 

[Starcraft Enterprise]

Re: Quick question- Replace 1969 MC-1 with 1981 Alpha?

Here is a puzzle. I started to switch out the drive shaft from my old outdrive to my new used one. I was comparing the drive shafts to try and figure out the difference between them and could not see one. The serial # on my old broken outdrive is 2583220. The serial # on my new used outdrive is 5493391. But the drive shafts was the same size. My old outdrive is a 1969 model. The guy I bought the new used one from said it was from a 1981 model boat.
Here are some pics. The first one is the drive shaft from the old outdrive. The second pic is the new used drive shaft. The third pic is the transom ring that came with the new used outdrive in case that helps with ID. It has the newer hydraulic manifold compared to mine. I went ahead and installed it without switching driveshafts and everything went together. Any thoughts?
Old driveshaft

Newer

Transom ring

pics

 

[Eric 3.7LX Alpha 1]

Re: Quick question- Replace 1969 MC-1 with 1981 Alpha?

That's easy... The 120 in '81 isn't an Alpha. You got yourself a MC-1 there. Does it have a lift ring on the top cover of the upper? Here's the chart:

direct fit.

Oh by the way. If you already got the impeller for an Alpha one, you can use it in your MC-1 EXCEPT for the lower water pump housing. The lower water pump housing is different from MC-1 to Alpha One, and damage will result.

That lower unit (both of yours) will have preload pin on the top of shaft. Alpha Ones don't.

Here's a pic of the pin on the top shaft.