• Mercruiser lower parts drawing 51-77

Lower unit outdrive with break down drawing

Updated April 12th 2026

• Alpha One (Generation 1 up to 1990) and Mercruiser outdrive lower unit components
• Drive shaft, prop shaft
• Water pump kits, oil seals
• GLM Marine numbers with OEM Mercury cross reference

Mercruiser outdrive parts drawing 51-77

Photo

Description / OEM #

Price
(USD)

Price (Canadian)

Lower Unit 1623 - 8951A43

Item A
SEI SE106

Aftermarket Alpha 1 lower gear case

Alpha One Gen 1 / MerCruiser complete lower unit replacement.

Years 1970 to 1990 models, serial numbers 2791957 – OD469858

13 spline drive shaft

4, 6 and V8 engines.

OEM 1623 – 8951A43

$1125.96

$1499.89

21131 Cross pin

Item 51

 

21131

 

Cross pin

 

17 – 8M 0020941

$4.95

$ 6.89

11060 Clutch dog

Item 52

 

11060

 

Clutch dog

 

52 – 853594T

$225.95

$ 297.89

Propeller Shafts

Item 53

 

11155 Propeller shaft

 

44 – 850308

$660.95

$ 630.89

23290 Shims

Item 54

23290

 Shim

15 – 97166

$4.95

$ 6.89

23141 thrust ring

Item 55A

23141

 Thrust ring

Years 1970 to 1982

35915

$26.95

$ 36.89

23140

Item 55B

 

23140

 

Thrust ring

Years 1983 and up

 

26 – 816575 A2

$11.95

$ 15.89

21620

Item 56

21620

Bearing

30 – 88957T

$37.95

$ 56.89

83445 O ring

Item 57

83445

O rings ( 5 units )

25 – 896524

$10.95

$4.89

11410

Item 58

11410

Prop shaft bearing

31 – 30956

$10.95

$12.89

11405 Bearing carrier

Item 59

11405

Bearing carrier

818763 A10

$157.95

$ 263.89

85130 Oil seal

Item 60

85130

Oil seal (inside)

26 – 14077

$7.95

$ 13.89

85700 Oil seal

Item 61

85700

Oil seal (outside)

26 – 12224

$12.95

$ 20.89

11080 Key

Item 62

11080

Key

28 – 30281

$4.95

$4.89

11380

Item 63

11380

Keyed washer

*For gears, see part number 43

14 – 79447

$6.95

$ 10.89

21120

Item 64

21120

Cover nut

8M 2011027

$18.95

$ 29.89

21301 Thrust hub

Item 65

21301

Thrust hub

12 – 835467Q 01

$22.95

$ 37.89

21760

Item 66

21760

Lockwasher

13 – 42351 – 1

$5.95

$4.89

21360 Receiver

Item 67

21360

Washer

12 – 31211 Q03

$6.95

$10.89

21200

Item 68

21200

Tab washer

14 – 816629Q

$4.95

$ 6.89

21230 Propeller nut

Item 69
P/N 21230 Lock nut

11 – 52707 Q1

$8.95

$ 15.89

Drive Shafts

Item 70

11110

Drive shaft with pre load pin at top (1967 – 1983 only, serial numbers 2791957 – 6225576

45 – 41939 F1

$432.95

$ 176.89

11120 Drive shaft

Item 70B

11120

Drive shaft

Years 1984 to 1990

serial numbers 6225577 –  0D469858

45 – 42634

$533.95

$ 182.89

21330 Lower unit slinger

Item 71

21330

Slinger

25 – 30271

$4.95

$4.89

11020 Lower unit reverse gear 1972 to 1982

Item 72

11020

Reverse gear

 (1972 – 1982, serial numbers 3469428 –  6225576)

43 – 92320T

$389.95

$ 386.89

21413 Dowel pin

Item 73
P/N 21413 Dowel pin

17 – 35973

12110 Water pump kit

Item 74A

 

P/N 12110

 

Water pump kit

 

(1970 – 1983, serial numbers 2763442 – 6854392)

$44.95

$ 66.89

12120 Alpha 1 pump

Item 74B

 

P/N 12120

 

 Impeller kit with housing

 

(1984 – 1990 Alpha One serial numbers 6854393 – OD469858)

$37.95

$ 63.89

Item 76

12754

Aluminum anode kit

888756Q 04

$25.95

$ 40.89

87510 seal kit

Item 77

 

87510

 

Seal kit

 

26 – 33144 A2

$38.95

$ 66.89

Mercruiser Lower Unit Parts 1 – 25