spanky- block casting 3733950 checks to be 54/55 date. Block should contain crank forging 3701486 or 3701488. Rod forgings should be 3702448 or 3836456. That's to say if the rebuilder used the stock internals anyway. My info tells me head 3835913 is 235, 55, I think, but don't know for sure. I have seen other early 261 54/55 blocks without the captains bars. Just depends on the casting. I can tell you that Chevy made 3 different 261 engines from early 54 thru late 55. The early 54 engines with small diameter cam bearings and shim pak mains. The late 54-early 55 engines with large diameter cam bearings and shim pak mains. And the late 55 engine minus the shim mains. Your engine should have the high water pump and 6 volt starter, based on the casting. The original COE engines differ from the conventional cab model engines, as the exhaust manifold is unique in that it exits to the rear. Your engine should also have the offset air cleaner and may be Carter YF equipped. Check the suffix code on the engine. 54 261 engines start with N, or Q. Early 55 261 engines start with F, N, or Q. And to make it more confusing late 55 start with F, TD, or TA. There was a certain amount of overlap with the changes in the 235/261 engines and the changes in trucks from Advanced Design to Task Force, all taking place in less than a 1 1/2 year span. From what I have read the Flint plant could not keep pace with the engine assemble line so some 235 and 261 truck engines were made at Tonowanda were shipped out directly to the truck assembly plants. The NY plant usually did not make the 261 truck engines, but made car engines and light truck engines. COE trucks are way
