Attwood Marine 66061-3
Listed flange: 3½ in
Polished stainless steel; retaining chain; listing specifies 1½-inch associated fill hose.
Marine Deck-Fill Caps: Attwood & Whitecap MPN Guide
Marine deck fills can have similar-looking caps and outer flanges but different threads, gaskets, key slots and fluid markings. The Attwood and Whitecap products below are compared by their original manufacturer numbers and listed dimensions so you can identify the existing fitting before replacing a cap or complete assembly.
Identify the original deck-fill fitting
Look for the brand and part number on the existing deck fill. Inspect the cap's actual mating threads, gasket, key slots, attached chain and the fluid marking. Confirm whether you need only a replacement cap or the whole deck-fill assembly; their dimensions and supplied components can differ.
A 3-inch flange is not a universal cap size. It describes the outer mounting area, not the replacement cap's mating diameter or thread profile. Similarly, a 1½-inch hose specification applies to the corresponding fill body and does not prove that two loose caps interchange.
Attwood and Whitecap deck-fill MPN comparison
These measurements are identifying references from the exact product listings. Confirm the fluid marking and cap interface with the original installation before purchasing.
| MPN | Manufacturer | Listed flange | Product |
|---|---|---|---|
| 66061-3 | Attwood Marine | 3½ in | View |
| 66074-3 | Attwood Marine | 3 in | View |
| 6061C | WhiteCap Industries | 3 in | View |
| 6123C | WhiteCap Industries | 3 in | View |
Compare matching store products
Attwood Marine 66074-3
Listed flange: 3 in
Polished stainless steel; retaining chain; listing specifies 1½-inch associated fill hose.
WhiteCap Industries 6061C
Listed flange: 3 in
Stainless steel; retaining chain; confirm correct fluid marking and original fill.
WhiteCap Industries 6123C
Listed flange: 3 in
Stainless-steel gasoline-marked deck fill product with retaining chain.
Frequently asked questions
Will an Attwood cap fit a Whitecap deck fill with the same flange diameter?
Not necessarily. Match the original deck-fill manufacturer part number and confirm the cap threads, gasket and sealing arrangement. A matching outer flange alone cannot establish compatibility.
What differs between Attwood 66061-3 and 66074-3?
The product listings identify different outer flanges: 3½ inches for 66061-3 and 3 inches for 66074-3. Check the actual cap interface separately; the outer dimension does not prove interchangeability.
Can the Whitecap 6123C be used for water filling?
6123C is identified for a gasoline application. Marine deck fills need correct permanent identification and a matching dedicated tank connection. Do not substitute a fuel-marked fill for a water fill.
Does a deck-fill retaining chain determine compatibility?
No. The chain helps retain the cap when open, but has no bearing on thread and seal interchangeability.
Related marine deck-fill parts
Identify Sea-Dog Deck Fill Caps, Keys and Emergency Plugs
Inspect sealing surfaces and follow the vessel manufacturer's instructions, particularly where the connection carries fuel.
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