Alpha one drive question

[s.hadley81]

Hey guys,
Does this B stamped on my drive next to the serial number mean anything? I only noticed it this off-season when I pulled my drive for the winter because it was covered by the decal which finally gave up. It was not stamped thru the decal like the serial number, it was only visible once I pulled the decal off.

 

[s.hadley81]

 

[mickyryan]

hmm its odd don't look like its even same size as other stamping so who knows maybe som0one just goofing off or a inspectors letter

 

[Fun Times]

If I can read your serial number correctly it reads 0B564370 which would be an 1987 MERCRUISER MC1 1.98:1 Model Number 01981017.

The B marking is probably just another quick mark for the factory guys to know easier what gear ratio the drive should be in order to mark it properly later on and/or for possible I/Ding for servicing later on in life. The info from manual # 6 section 3 page 3A-8 below suggests the second place to look to help locate the gear ratio though I've seen lettering like that there under the decals before too.

Drive Unit Gear Ratio Identification All drive unit gear ratios are identified on each drive in two places. It is important to note the ratio of the drive unit before proceeding with any repairs. The first place to look is on the decal on the port side of the drive housing. It will have a number such as (1.50R) and then the seal number. The second place to look will be on the universal joint splined yoke. It will be identified with a letter such as (F). This method is explained in the following chart.
ALPHA
B = 1.98:1 & 1.94:1
C = 1.65:1 & 1.62:1
D = 1.84:1 & 1.81:1
F = 1.50:1 & 1.47:1
H = 1.32:1 & 1.29:1
M = 1.50:1 & 1.47:1 MAGNUM.

This will be true for new drive units or drive units that have not been serviced. A drive unit could have had the gear ratio changed for high altitude or had the lower unit gears changed to a more recent version, which would void out any application of the above chart. The gear ratio would then have to be determined by counting the teeth on the drive gear and the driven gear in the drive shaft housing and using the following chart for reference.
ALPHA Ratio Drive Driven
1.98:1 & 1.94:1 20 24
1.84:1 & 1.81:1 17 19
1.65:1 & 1.62:1 24 24
1.50:1 & 1.47:1 20 22
1.32:1 & 1.29:1 20 16

 

[s.hadley81]

Thanks a lot Fun Times ,that's some good info there. You answered my question plus some!