Mercury MerCruiser Blackhawk Lower Gear Retainer Nut 805070
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Mercury MerCruiser 805070 is a genuine OEM retainer nut used in the lower gears and components assembly of the MerCruiser Blackhawk stern drive. Current Mercury dealer references show 805070 superseded to 805538, the functional replacement part number.
Key Features
- Genuine Mercury Marine OEM part number 805070.
- Superseded to current replacement part number 805538.
- Used as the retainer nut in the lower gears and components section.
- Current dealer shipping specs for 805070 are approximately 0.14 lb, 2.25 in. x 2.25 in. x 0.25 in.
- Current dealer shipping specs for 805538 are approximately 0.23 lb, 2.50 in. x 2.50 in. x 0.50 in.
Engine Compatibility
The strongest supportable fitment for 805070 is the MerCruiser Blackhawk stern drive in the lower gears and components assembly. Current OEM-style diagram references place the replacement 805538 in that Blackhawk lower-gear layout with the surrounding driveshaft, coupling, bearing, thrust bearing, and propeller shaft parts.
Serial Number Fitment Notice
Verify fitment by exact drive model, serial number, and the correct lower gears and components diagram before ordering. For 805070, the safest match is the specific Blackhawk lower-unit assembly location rather than the part name alone.
When This Part Needs Replacement
Replace this retainer nut when the original is damaged, worn, corroded, distorted, or removed during lower-unit service and no longer suitable for reuse. Because it is part of the lower-gear retaining stack, correct condition and exact fit matter during gearcase reassembly. This is a practical service inference based on its documented placement in the Blackhawk lower-gears assembly.
Installation Notes
Install this part only after confirming the correct Blackhawk parts diagram for the drive being serviced. Current diagram references show the replacement 805538 used with related parts such as washer 805068, driveshaft assembly 805067A1, bearing assembly 36387A1 / 8M0146566, coupling assembly 88243A3, and inner propeller shaft 805073T / 865322T in the same lower-gear service area.
Alternate/Superseded Part Numbers
Current Mercury dealer references show 805538 as the superseding replacement for 805070.
Parts Desk Insight
For lower-unit hardware like this, the exact drive family and diagram position matter more than the nut description. Matching the retainer nut to the Blackhawk lower-gear breakdown is the best way to avoid ordering the wrong hardware for the assembly.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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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.
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