Skooter -- The experts will chime in soon, but in the meantime, all I can tell you is that not all 261's have the "Captain's Bars"
My 261 is a crate motor out of the 3733950 mold (for the ''54 qand '55 1st series trucks). There may be more than one mold for the 261's built for the last of the Advance Design Trucks (with the high water pump). Someone with better access to a casting code decoder ring can tell you for sure about your code. You also need to decipher the date code, too.
v/r
John
