Mercury MerCruiser Quicksilver — Shift Crank Gear Housing Pin — Alpha One & Gen II — 379721
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Mercury MerCruiser Quicksilver Shift Crank Gear Housing Pin 379721 | Alpha One & Gen II
The Mercury MerCruiser Quicksilver 379721 is a genuine OEM shift-crank pin used inside the gear housing of select MerCruiser sterndrives. It is part of the lower-unit shift mechanism and provides the factory locating and pivot point the shift crank needs to operate properly. Mercury lists 379721 as the current replacement for the earlier pin 37972.
Key Features
- Genuine Mercury Marine OEM part
- Part number: 379721
- Full service number: 17-379721
- Product type: Shift Crank Gear Housing Pin
- System: Sterndrive gear housing, shift mechanism
- Quantity: 1 per applicable gear housing
- GTIN: 745061140097
- Current active Mercury service part
Compatible Applications
- MerCruiser R and MR sterndrives
- Alpha One Gen I
- Alpha One Gen II
- Standard- and counter-rotation gear housings where 379721 is specified
Serial Number Fitment Notice
Confirm the sterndrive model, serial number and gear-housing diagram before ordering. This pin is widely used, but lower-unit configurations changed across R, MR, Alpha One and Alpha One Gen II production.
When This Part Needs Replacement
Replace the pin if it is bent, worn, corroded, loose or damaged during gear-housing service. Excessive wear in the shift-crank mechanism can contribute to poor or inconsistent gear engagement.
Installation Notes
Install the pin in the original shift-crank position within the gear housing. Inspect the surrounding shift components and gear-housing hardware while the lower unit is apart, and follow the applicable Mercury service procedure when reassembling the shift system.
Related Parts
- 5356A4 — gear housing assembly, earlier R, MR and Alpha One applications
- 815822A36 — Alpha One Gen II gear housing assembly
- 8M0204680 — gear housing seal
- 46911 / 56298 — gear housing mounting studs
Alternate & Superseded Part Numbers
- 379721 / 17-379721 — current OEM number
- 37972 / 17-37972 — superseded by 379721
Technical FAQ
Does 379721 replace 37972?
Yes. Mercury lists 379721 as the current replacement for 37972.
Does it fit both Alpha One Gen I and Gen II?
Yes, where the gear-housing diagram specifies 379721. It also appears in earlier R and MR drives.
Does it work in counter-rotation gear housings?
Yes, in standard- and counter-rotation housings where 379721 is specified.
Parts Desk Insights
Best use: Replacing a worn or damaged shift-crank pin during Alpha One, Gen II, R or MR gear-housing service.
Most common mistake: Reassembling the lower unit without checking this small pin. A worn pin can cause sloppy or inconsistent shifting and mean reopening the drive later.
Sizing and fitment: Confirm your drive model, serial number and gear-housing diagram. If your diagram lists 37972, 379721 is the correct current replacement.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.