Here is a NOS exhaust manifold for 1939-1949 Chevrolet cab over (COE) and double duty (DD) trucks. GM PART number is 3690880. Manifold CASTING number is 3835440. The 2 mounting holes are 25 3/4 inches C-C and are 7/16 inch holes. There is surface rust from sitting on the shelf. Be sure to check my other listings. Be the only one on your block to own one of these.