Mc1 or pre alpha leg fit alpha on gimbal?

[Setiman]

Hi guys i have a pre alpha 1976 sterndrive ( the narrow one without side mounted trim sensor) which i have pulled the transom plate off to find its rotten. I have found locally a good second hand alpha one gen one transom, gimbal and bellhousing assembly. I just dont know if it will fit my older leg? Talked to a few local techs here and they sayit wont because of alpha gen one having an external oil resivour and the bolt pattern being different where the upper leg housing bolts to the gimbal. Yet most online things i can find say it will fit? Can anyone clear up this confusion?

 

[Fun Times]

Hi there, welcome to iboats! The Gen one Alphas or under year/model wise didn't use an oil reservoir new from mercruiser. That was an add on option which basically mounted to the transom of the boat by drilling a hole through the boats transom for the hose to connect to the drive shaft housing. The oil reservoir bulkhead fitting through the transom assembly / Gimbal Housing started to be used depending on model as an option on the Gen 2 Alpha drives 1991 - 1995 before becoming standard for 1995+.

http://www.mercstuff.com/reservoir.htm

See if the info in the two links below helps you out any too,
https://www.perfprotech.com/blog/art...a2-sterndrives

http://bluewatermarinesvc.com/html/mercruiser_fyi.html

Mercruiser Drive - Must Know Info:
1973 and earlier drives have a short shift throw and are not compatible with the 1974 and newer drives. So when replacing drives or swapping out gear cases. Keep this in mind.

The in-line number 1 drive before the R(redesigned), MR(mercruiser redesigned), and Alpha drives have a short splinded yoke 8 1/8 in (20.6cm) and the newer R, MR, and Alpha have a longer splined yoke of 9 9/16 (24.3cm). They will not interchange, as yoke and coupler damage will result.

The earlier number 1 drive and the R drive have a preload pin on top of the drive shaft on the lower gear case. This pin preloads the upper drive shaft bearing. The MR and Alpha drives have been redesigned where the gear angles have been changed as to push the pinion gear upward. So now the preload is in the opposit direction and the preload pin is no longer needed.

New replacement drive shafts in the lower gear housing have done away with the o-ring groove at the top of the shaft. This is for both drive shafts with and without the preload pin.

Mercruiser number one drive and the 1st generation alpha drive are interchangeable starting with the year of 1974. There will be a slight miss match where the drive attaches to the bell housing.

 

[Bondo]

I just dont know if it will fit my older leg?

Ayuh,.... Welcome Aboard,..... Yer old drive will bolt right onto the Alpha 1 transom assembly,....

But,.....
A few cautions,.....
Ya don't mention what motor,....
Various motors run different drive gear ratios,...
And,....
The ole MC-1 drives used with the GM In-line motors, uses a shorter input shaft on the drive,...
The Alpha 1s all use the longer shaft,....
The shorter shaft drive will bolt on, 'n run, but the coupler will blow out, 'cause there's 'bout an inch less of shaft engagin' the splines,...

Yer gonna run into problems inside the hull too,....
The motor mount spacin' changes, 'tween the ole MC-1s, 'n the Alpha 1s,...
You'll need the flywheel cover that fits yer motor,...

 

[Setiman]

Thanks for the info! The motor was an old 165 6 cyl chev. I took it out and found a 2008 volvo d3 160 diesel with 800 hours on the clock. Itsbeen working good for a few years so i have no problems realigning engine if need be. The ratios i thinks a 1.68? Its a bit low for my diesel but it still pulls 23 knots at 3000 rpm. The only other question i have is about the splined yoke, is the universal in the same position on both types? And is the external transom assembly longer hence longer splined shaft? Or is the yoke longer on the alpha only because the motor is further foward?

 

[Bondo]

The only other question i have is about the splined yoke, is the universal in the same position on both types? And is the external transom assembly longer hence longer splined shaft? Or is the yoke longer on the alpha only because the motor is further foward?

Ayuh,.... The u-joints are the same, the motor's end of the shaft is longer,....

I never measured to see where the inch comes from,...