• Mercruiser Alpha One Parts Drawing 1 to 25

Outdrive upper gear case components #1-25 with Exploded View Diagram

Updated April 19th 2026

• GLM Marine lower unit
• Upper gear case break down drawing
• Compatible with all stern drive models up to 1990
• Gears, drive shafts and u joints
• Mercury OEM numbers for easy cross reference

Mercruiser Alpha One upper gearcase

Photo

Description / OEM #

Price
(USD)

Price (Canadian)

87500

Item A

P/N 87500 Seal kit

26 – 32511 A1

$29.89

$39.89

12110

Item B
P/N 12110 Complete water pump kit

1970 to 1983 MC-1 and R models, serial numbers 2763442 – 6854392).

Click on picture for newer 1984 to 1990 Alpha One and 1991 and up Gen 2 models.

$51.89

$66.89

51220-51140

Item C
51220 – 51140

GM 4.3L V6 center rise exhaust kit with riser and gaskets. 1986 and up.

Click on photo for all other models.

99746 A17 – 807988 A2

$484.89

$629.89

SEI upper gear case

Item 1

SE106-UP New upper SEI upper gear case assembly.

All ratios available for 4, 6 cyl. and V8. Replaces most 1970 – 1990 models, MC-1, R / MR and Alpha 1 Gen 1, serial numbers
2791957 – OD469858)

Standard yoke shaft have the 9-9/16″ output shaft yoke. 

1547 – 9412 A20
1547 – 9412 A21
1547 – 9412 A22
26 – 33144 A2
1547 – 9412 A19

$1099.89

$1430.89

28400 Top cover assembly

28400 Top cover assembly (includes bolts, shims and bearing 1-25/32 inch o.d.)

94998 A4

$130.89

$170.89

80420

item 3
80420 O-rings (5)

25 – 32546

$11.89

$15.89

23260 Shim

Item 4A

23260 Shim (For No. 21510)

15 – 45691 A1

$14.89

$18.89

23261

Item 4B

23261 shims  For
bearing 21511
O.D. 1-25/32 inch

(Bore size 1.7813)

15 – 32563 A1

$12.89

$16.89

21510

Item 5A

21510 Bearing

( 1-15/16 inch O.D. )

25 – 32546

$36.89

$47.89

21511

Item 5B

21511 Bearing

( 1-25/32 inch O.D. )

25 – 32546

$19.89

$25.89

Drive Shaft

Item 6

 

11130 Vertical drive shaft

45 – 55796

$107.95

$141.95

80190

Item 7

 

80190 O-rings (5)

25 – 55801

$6.89

$8.89

11210 Heavy duty gear set

Item 8A

 

11210
Gear Set (1.50 or 1.47 Ratio 20-22 tooth count

V8 models up to 1997

43 – 18410A4

$430.89

$559.89

gear set

Item 8B

 

11220
Gear set ( 1.65 or 1.62 Ratio )
( 24-24 ) for 165 and inline 6 cyl. models

Years 1970 to 1997
serial numbers 2763442 – K999999

43 – 45814A5

$268.89

$348.89

11230

Item 8C

 

11230
Gears ( 1.84 or 1.81 Ratio ) ( 17-19 ) for V6 models up to 1997

43 – 75325A3

$337.89

$438.89

11240-4 cylinder 43-55778A3

Item 8D

 

11240
Gears ( 1.98 or 1.94 Ratio ) ( 20-24 ), for 120/140 and 4 cyl. models up to 1997

43 – 55778A3

$320.89

$416.89

21560 Alpha One

Item 9A

 

21560
Roller bearing (1.50 Ratio)

31 – 32573 A1

$52.89

$68.89

21540

Item 9B

 

21540

Roller Bearing
( 1.65, 1.84, 1.98 Ratio )

31 – 35990 A1

$39.89

$50.89

23270 Mercruiser Alpha 1 shim kit

Item 10

23270
Shims

15 – 36178 A1

$14.89

$18.89

85020 Oil seal

Item 11

 

85020

Oil seal

26 – 32511

$16.89

$21.89

85060

Item 12

 

85060

Oil seal

26 – 96503

$11.89

$14.89

81180

Item 13

 

81180

O rings (5) units

26 – 32511

$4.95

$5.95

28050 Drive shaft parts with internal lock ring

Item 14

28050

 

U-joint assembly (includes drive shaft, universal joints, socket and short yoke

814819 A2

$392.95

$518.95

28315 Drive shaft

Item 15
28315

 

Drive shaft – new and used shafts available.

814819 A3

$147.89

$191.89

28030 U-Joint

Item 16

P/N 28030 U-joint

 

75832 T1

$52.89

$68.89

28100 Socket

Item 17

P/N 28100 Socket ( universal joints sold separate )

39383T

$89.89

$115.89

28310 Yoke

Item 18

P/N 28310 Yoke (short)

46020 – 1

$79.89

$102.89

28350 Retainer

Item 19
P/N 28350 Retainer

816811 – 1

$28.89

$37.89

28390 Ring

Item 20

P/N 28390

Ring

35983

$14.89

$19.89

82380

Item 21

P/N 82380

O ring

 

( 5 units )

25 – 70937

$12.95

$15.95

28370 Alpha Carrier Assembly

Item 22

P/N 28370

 

Carrier assembly

25 – 70937

$51.89

$66.89

85030

Item 23

P/N 85030

Oil seal

26 – 823894

$18.89

$23.89

21520

Item 24

P/N 21520

 

Double bearing with spacer. Compatible with all ratios except 1.32.

31 – 35988 A2

$179.89

$234.89

23280

Item 25

P/N 23280

 

Shim

15 – 35980 A1

$21.89

$27.89

Numbers 26-48