Tom,
Here are some more photographs of the 261 blocks.
This is the casting number on
3733950 block in my roadster. Here is the
driver's side of the 3733950 block. This is the
driver's side of the 3835911 block. It is hard to believe that someone has altered the casting number on the blue block from 3733950 to 3835911. There would be some marks left from where the final two digits (the "5' and "0") were cast into the block. The shadows and flash reflections on my images make the surface look a lot rougher than it does with the eye and diffuse light. Also, a good friend of mine was involved with the original purchase of the blue block and its subsequent history, and he would have been aware of any alteration.
The blue block surface is also very clean where the captain's bars would be. As the images show, a circular boss is cast into the 3835911 block on the driver's side where the captain's bars are located on the 3733950 block.
I had never noticed that the
Chevrolet Parts Catalog shows the 3835911 casting number for two different part numbers. Which of the 3835911 blocks have the small cam bearings?
I would like to see what the markings on some other 3835911 blocks looked like. It appears that Chevrolet used that casting number for more than one application.
Hoyt
