MerCruiser MR/Alpha One Gear Housing Diagram
| Ref | Part # | Note | Qty | Description |
|---|---|---|---|---|
| - | 1623-8951A43 | 1 | Gear housing assembly - complete | |
| 1 | 1623-8951A37 | 1 | Gear housing assembly | |
| 2 | 17-37972 1 | 1 | Shift crank pin | |
| 3 | 16-46911 | 1 | Stud (7/16-20 x 3-3/16”) | |
| 4 | 16-56298 | 2 | Stud (7/16-20 x 1-31/32”) | |
| 5 | 16-56297 2 | 1 | Stud (5/16-24 x 3-3/8”) | |
| 6 | 16-69501 | 2 | Stud (1/4-28 x 3-1/4”) | |
| 7 | 26-45577 1 | 1,2 | 1 | Seal |
| 8 | 17-35973 | 2 | Dowel pin | |
| 9 | 31-42647A 1 | 1 | Roller bearing | |
| 10 | NLA | 1 | Water pickup insert (starboard) | |
| 11 | 93424 1 | 1 | Water pickup insert (port) | |
| 12 | 10-76156 | 1 | Screw | |
| 13 | 11-45812 | 1 | Nut | |
| 14 | NLA | 1 | Dowel pin | |
| 15 | 45-42634 | 1 | Driveshaft assembly | |
| 16 | 15-42637A1 | AR | Shim kit | |
| 17 | 31-36387A1 | 1 | Tapered roller bearing assembly | |
| 18 | 824519 1 | 1 | Retainer | |
| 19 | 43-878087A4 | 1 | Gear set (forward & pinion) | |
| 20 | 12-92721 | 1 | Washer | |
| 21 | 11-35921 | 1 | Nut (5/8-18) | |
| 22 | 10-67892A1 | 1 | Screw | |
| 23 | 12-19183 3 | 1,2 | 1 | Washer |
| 24 | 46-44292A3 | 1 | Water pump base assembly | |
| 25 | 27-42631 1 | 1,2 | 1 | Gasket |
| 26 | 25-90011 | 1,2 | AR | O-ring |
| 25-38099 | 1 | AR | O-ring | |
| 27 | 26-89238 | 1 | 1 | Oil seal |
| 28 | 26-16977 | 1 | 1 | Oil seal |
| 29 | 27-85608 1 | 1,2 | 1 | Lower gasket |
| 30 | 27-858524 | 1,2 | 1 | Upper gasket |
| 31 | 32435 1 | 2 | 1 | Face plate |
| 32 | 46-96148T1 | 2 | 1 | Water pump body assembly |
| 33 | 48752T | 2 | 1 | Insert |
| 34 | 26-38970 | 2 | 1 | Water inlet tube seal |
| 35 | 47-89984T4 | 2 | 1 | Impeller |
| 36 | 28-56654 | 2 | 1 | Impeller key |
| 37 | 10-96411 | 2 | 1 | Screw |
| 38 | 11-826711 9 | 2 | Nut (1/4-28) | |
| 39 | 12-29245 | 2 | Washer | |
| 40 | 11-13436 | 1 | Nut (5/16-24) | |
| 41 | 12-36001 | 1 | Washer | |
| 42 | 25-30271 | 2 | 1 | Rubber ring |
| 43 | 25-30613 | 1,2 | 1 | O-ring (driveshaft) |
| 44 | 25-29804T | 2 | 1 | Guide sleeve |
| 45 | 77481 1 | 1 | Lower shift shaft | |
| 46 | 53-29641 | 1 | Retaining clip | |
| 47 | 12-27880 | 1 | Washer | |
| 48 | 25-25439 | 1 | 1 | O-ring |
| 49 | 23-30617A2 | 1 | 1 | Shift shaft bushing assembly |
| 50 | 26-89236 1 | 1 | Oil seal | |
| 51 | 12-31266 | 1 | 1 | Rubber washer |
| 52 | 12-29395 | 1 | Shift shaft washer | |
| 53 | 76865 | 1 | Shift crank | |
| 54 | 18-46950 1 | 1 | Cotter pin | |
| 55 | 818349T1 | 1 | Shift spool assembly | |
| 56 | 15-47397A1 | AR | Shim kit | |
| 57 | 31-35928T1 | 1 | Tapered roller bearing assembly | |
| 58 | - | 1 | Forward gear (see #19) | |
| 59 | 31-42679 | 1 | Roller bearing (Torrington # GB-1616) | |
| 31-30895T | 1 | Roller bearing (Torrington # B-1616) | ||
| 60 | 52-853594T | 1 | Sliding clutch | |
| 61 | 17-30632 | 1 | Cross pin | |
| 62 | 24-30893 | 1 | Spring | |
| 63 | 44-824110 | 1 | Propeller shaft | |
| 64 | 43-824109A1 | 1 | Reverse gear | |
| 65 | 68100 1 | 1 | Thrust ring | |
| 66 | 30-88957T | 1 | Ball bearing | |
| 67 | 25-31534 | 1 | 1 | O-ring |
| 68 | 73020A14 | 1 | Bearing carrier (casting 73020C) | |
| 818763A10 | 1 | Bearing carrier (casting 73020C1) | ||
| 69 | 31-30956T | 1 | Roller bearing | |
| 70 | 26-76868 | 1 | 2 | Oil seal |
| 26-14077 | 1 | Inner oil seal (Fishline cutter seal) | ||
| 26-12224 | 1 | 1 | Outer oil seal (Fishline cutter seal) | |
| 71 | 28-30281 | 1 | Key | |
| 72 | 14-79447 | 1 | Tab washer (use with Black Max props) | |
| 14-18323 | 1 | Tab washer (use with MC-I props) | ||
| 73 | 79448 | 1 | Retainer ring | |
| 74 | 12-835467Q01 | 1 | Thrust hub (use with Black Max props) | |
| 56292A4 | 1 | Thrust hub (use with MC-I props) | ||
| 75 | 12-31211A3 | 1 | Splined washer | |
| 76 | 14-816629 | 1 | Tab washer | |
| 77 | 11-52707Q1 | 1 | Propeller nut | |
| 78 | 31640Q4 | 1 | Trim tab (2-3/8”) | |
| 34127T2 | Opt | Trim tab (4”) | ||
| 79 | 10-32470 | 1 | Trim tab screw | |
| 80 | 10-30206 | 1 | Screw | |
| 81 | 11-34933 | 2 | Nut | |
| 82 | 13-42351 1 | 1 | Lockwasher | |
| - | 26-33144A2 | - | Gear housing seal kit | |
| - | 46-96148A8 | - | Water pump repair kit | |
| - | 43-803091T1 | 3 | - | Lower unit rebuild kit |
| - | 43-803090T1 | 3 | - | Seal & bearing kit |
Note 1: Contents of seal kit QS-26-33144A2
Note 2: Contents of water pump repair kit QS-46-96148A8
Note 3: Rebuild kit includes all gears, shims, bearings, seals, clutch & prop nut to rebuild upper lower unit
AR: As required