Sierra U-Joint Cross Bearing 18-2104, Replaces 75832A2, Fits Alpha I and TR/TRS Units

The Sierra 18-2104 is a heavy duty U-joint cross bearing (universal joint) designed for use in the gimbal/drive shaft coupling of outdrive units. It transmits rotational power through an angled connection while allowing the drive shaft to articulate, a wear point that requires periodic replacement as boats accumulate hours. This U-joint is built to heavy duty specification for durable service under continuous marine loads.

Each unit includes both a straight grease fitting and a 90 degree grease fitting, giving installers flexibility to fit the zerk fitting in whichever orientation clears surrounding components during service, which simplifies routine lubrication once installed. The cross bearing is intended as a direct fit replacement for the OEM part it supersedes, using the same mounting geometry and bearing cup arrangement as the original equipment.

The Sierra 18-2104 fits all #1 and ALPHA I units within serial number range 1684188-B418818, and also fits TR/TRS and II SSM drive units. Because it is designated for this specific serial number range and unit type, confirm your outdrive's serial number and unit designation before ordering to ensure correct fitment.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2104
• Product Type: U-Joint Cross Bearing
• Duty Rating: Heavy Duty
• Grease Fittings Included: Straight and 90 degree
• Product Dimensions: 3.5 x 3.5 x 1.25 inches
• Weight: 1.22 pounds
• Exterior Finish: Machined
• Country of Origin: China
• UPC: 030999310293

Fitment

• Fits all #1 and ALPHA I units, S/N 1684188-B418818
• Also fits TR/TRS and II SSM units

Replaces (OEM)

• 75832
• 75832A2
• 75832T
• 758321
• 75832T1
• 75832A1
• 75832A3
• 58749
• 41431
• 36312

Frequently Asked Questions

What does the Sierra 18-2104 U-joint replace? The Sierra 18-2104 replaces OEM numbers 75832, 75832A2, 75832T, 758321, 75832T1, 75832A1, 75832A3, 58749, 41431, and 36312.

What units does the 18-2104 U-joint fit? It fits all #1 and ALPHA I units within serial number range 1684188-B418818, and also fits TR/TRS and II SSM units.

How much does the 18-2104 U-joint weigh? The Sierra 18-2104 U-joint cross bearing weighs 1.22 pounds.

What are the dimensions of this U-joint? The Sierra 18-2104 measures 3.5 x 3.5 x 1.25 inches.

What grease fittings come with the 18-2104? Both a straight grease fitting and a 90 degree grease fitting are included with the Sierra 18-2104, so the installer can choose the orientation that clears surrounding components.

Is the Sierra 18-2104 a heavy duty U-joint? Yes, the 18-2104 is built to a heavy duty specification for durable service in the drive shaft coupling of the outdrive.

How do I know if this U-joint fits my outdrive? Check your outdrive's unit type and serial number; the 18-2104 fits #1 and ALPHA I units in the S/N range 1684188-B418818, and TR/TRS and II SSM units. Confirm your serial number falls in that range before ordering.

Is the 18-2104 a genuine Sierra part or aftermarket? The 18-2104 is manufactured and sold under the Sierra brand as a direct replacement for the listed OEM cross-reference numbers.

Where is the Sierra 18-2104 manufactured? The Sierra 18-2104 U-joint cross bearing is manufactured in China.

What is included when I order the 18-2104? Ordering the Sierra 18-2104 includes the U-joint cross bearing along with a straight grease fitting and a 90 degree grease fitting.

Can the 18-2104 be used on TR/TRS units? Yes, in addition to #1 and ALPHA I units, the Sierra 18-2104 also fits TR/TRS and II SSM units.

Does the 18-2104 fit Alpha One drives outside the listed serial number range? The Sierra 18-2104 is designated for ALPHA I units within S/N range 1684188-B418818; units outside this serial range should be verified against a different part number before ordering.