Try a wet compression test. Just squirt a spoon full of motor oil in spark plug hole before doing test. This will temporally seal piston rings that may be the problem.
The bars are the same. Only the bracket is different. The 4 hole style is 1940 Ford and Mercury. The other bracket with an oval hole and 2 round holes is 1941 Ford and Mercury.
I have seen many of these on farm trucks. The purpose was to increase the load capacity so the owner could haul more weight. I think most of these caused early failure due to the abuse they encouraged.
Only if you are building a rod. There are many differences from 1936 to 1940 but the overall size is the same. I have a pair of the cowl support brackets you mentioned that came out of a 1940.
I have a fondness for the COE. My collection includes a 1939 101" dump, 1940 with a 5th wheel, 1941 Holmes twin boom wrecker, 1947 stake bed. I also have a nice pair of the rear dual wheel fenders.
Reading the original question from Kurt V, I think he wants to remove the line that is inside of the tank. The answer should be NO. The pick-up tube is riveted and soldered to the tank and is difficult to repair even after the tank has been removed.
I had the same problem on a 1934 pickup. Every thing on a pickup is the same as a car except the pitman arm. Because the column is tilted higher to fit the truck cab the splines in the pitman are clocked one tooth. Most pitman arms have a part number on them. Prefix 40- is car 46- is pickup...