Approved Spark Plug Tables

[AlvinMcIver]

There have been many questions raised and discussion had concerning approved spark plugs for the A-65. Attached (if I did this correctly) is a copy of the Type Certificate Data Sheet for the Model A-65 (which, as Norm pointed out in one of the posts, hasn't been updated in a "zillion years"). Also attached is TCM Service Information Letter SIL 03-2B which was last revised 10/26/2004, the stated purpose of which Is to "provide listing of currently approved spark plugs for TCM Engines" including the A-65. I notice that the REM37BY (about which Mike asked which document ok'd it use) is included in the SIL but wasn't in the TCDS.
Question I have is to what the numbers in the "Barrel Size" refer (e.g. 5/8 24) and just what is the Barrel on a spark plug. Thanks.
Alan Thiel
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