Attwood Lock'N-Pin 3/4-Inch Seat Bases: Threaded vs Non-Threaded

Replacing the base beneath a boat seat? Attwood's Lock'N-Pin 3/4-inch system has several 7 × 7-inch plates that differ in threading, bushing material and required deck opening. Matching the footprint alone isn't enough.

How the seat pedestal system fits together

Seat mountAttaches beneath the seat and connects to its specified pedestal hardware.
Pedestal postThe Lock'N-Pin name refers to the 3/4-inch locking pin system. The tube itself has a different outside diameter; verify your exact post.
Deck baseThe plate is mounted to the boat deck. A threaded post needs its specified threaded base, while a non-threaded post needs the matching non-threaded fitting.

Compare Attwood Lock'N-Pin base part numbers

All six models shown below have 7 × 7-inch square plates and are listed by Attwood as ABYC Type B components. Opening and clearance figures describe the specified base, not the deck's fastener-hole pattern.

Attwood MPN Threading Material Bushing Deck opening Below-deck depth
67729 Non-threaded Zinc-plated steel Acetal 2.75 in 2.5 in
67729-T Threaded Zinc-plated steel Acetal 2.75 in 3.5 in
6773 Non-threaded Stainless-steel finish; steel lip tube Bronze 2.75 in 2.5 in
6773-T Threaded Stainless-steel finish; steel lip tube Bronze 2.75 in 3.5 in
67739 Non-threaded Stainless-steel finish; steel lip tube Acetal 2.75 in 2.5 in
67749 Non-threaded Clear-coated aluminum Acetal 3.5 in 2.5 in
Important difference: Attwood 67749 requires a 3.5-inch deck opening, while the other five bases in this chart use 2.75-inch openings. The threaded 67729-T and 6773-T also need 3.5 inches below deck, compared with 2.5 inches for the listed non-threaded bases.

Measure before selecting a replacement

  1. Read the exact MPN. The “-T” ending distinguishes threaded versions of 67729 and 6773; do not treat them as interchangeable with the corresponding non-threaded bases.
  2. Identify the bushing. Attwood lists acetal bushings for 67729, 67729-T, 67739 and 67749; the 6773 pair uses bronze bushings.
  3. Check the deck cutout. Compare the required hole diameter with the actual installation. Do not assume the 7 × 7-inch outside size determines the cutout.
  4. Allow room below the deck. Threaded versions in this comparison extend farther beneath the mounting surface.
  5. Confirm the full seat system. These are Type B components and are not intended for helm or driver seating. Attwood does not recommend mixing its Lock'N-Pin seating hardware with components from other manufacturers.

Find the exact seat pedestal base

Compare the manufacturer numbers above, then check the corresponding product details and supplied components. NewRVParts ships from supplier warehouses; products are not available for warehouse viewing or pickup.

Using the larger 238 Series instead?

If your existing pedestal uses a 2-3/8-inch 238 Series post, see our Attwood 238 Series seat mounts and socket bases guide. These are different hardware systems, so match the complete original configuration rather than choosing by brand alone.

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