. Hi Nick, The 37 - 54 engines are same length. The 1955 - 63 six cylinder engines have a longer water pump.
An adapter is available to attach the short pump which is preferable to buying a shortened 55+ pump. You appear to have a 3 speed trans that's 12 inches long. You must use the correct 3 or 4 speed trans to attach the clutch and brake pedals. 1937 - 39 thans had spur cut low gear. 1940 - 46 had helical low gear. All trucks and commercial and trucks made 1939 and before had Spiral bevel differential gears. 1940 and newer have hypoid gears. 1940 and older trucks (NOT light commercial) had torque tube rear end. 1941 and later trucks had hotchkiss. You have a light commercial open express commonly called a pickup truck which is confusing. If you find a torque tube truck rear end with hypoid gears and a torque tube, it's a 1940. The 1940 trucks also used roller bearings in the U-joints.
The 3 speed used in taxi, police, One ton and Double duty used bearings in the counter shaft. the half tom commercial had bushings. If you have a 1940 trans in your truck with bushings, you can put the counter shaft from a 1954 or newer with bearing in the case.
Sorry to go into so much detail. Lou .
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