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Thanks for your help. I found the serial number to be an auto-blend too. I can confirm it is not an auto-blend since it doesn’t have an oil tank.The following is (or ought to be) your part’s catalog,
Mariner 40C (Twin Carburetor) (W / Auto-Blend) Outboard Motor Parts by All Engine Parts & Diagrams
Lookup Mariner 40c (twin carb) (w/auto-blend) outboard motor parts by component and buy discount parts from our large online inventory.www.marineengine.com
And the only reason why I put it as a questionable was because the ones in the following were sort of close to consider it to be a match but isn’t when searching the options.
Mariner 40 (Twin Carburetor) (W / Oil Injection) Outboard Motor Parts by Serial Number Range
Lookup Mariner 40 (twin carb) (w/oil injection) outboard motor parts by serial number range and buy discount parts from our large online inventory.www.marineengine.com
Using your serial number in a parts search suggests your model number to be 7040716 making the engine year to 1986 (ELO) as far as Merc was concerned.
Parts Group:40 HP MARINER: Options: Electric start, long shaft (20”/508mm) driveshaft housing. Remote control steering.
Oil injection standard.
Model style: ELO
CongratulationsUse another approach !!!!----I can find your model with 6 digit serial #.