Originally Posted by Gdads51
Skooter,

I did a little more searching and came a cross this quote in a VCCA chat conversation about 261 casting code locations: "The block codes are in various places on the fuel pump side of the engines. The casting number on my 261 which I believe to be 54-57 is located in front of the fuel pump down low near the oil pan."

Sounds like one last good spot to clean and check. I think the indication is the number is down just above the oil pan flange, right in the midst of all that wonderful crud in front of your fuel pump mounting boss. Sorry dang
Bingo. 3733949 Although I'm finding that number as a 235 casting number, not the 261 indicated by the serial number. frown Will be up bright and early to pull head and measure cylinder bore.
Attachments
IMG_9868.jpeg (567.88 KB, 147 downloads)

Last edited by Skooter; 02/18/2023 4:52 AM.
Matthew 6:33

1952 Chevy 1/2-ton 3100
Late '55 235/SM420/torque tube 3.55
Dalton Highway survivor (using original 216)
www.truckwithaheart.com