!936 was the first year for the Chevrolet line to offer a steel structured body with steel structured doors. These were available ONLY in the Standard line of cars. The 1936 Masters and 1936 Pickups were still wood structured with wood structured doors. 1937 the entire line shifted to the new style of construction.
I have seen some 36s with steel construction, but their numbers are few, 37 was pretty much all steel, except the sedan delivery models, they were loaded with wood, even in 37.
I have three '36 Chevy bodies. Two coupes and a short, no trunk 2-door sedan. All still have wood in the body. Both coupes have wood framed doors. The 2-dr has steel framed doors. I was told the 2-dr steel doors were introduced as a mid-year running change, but only on that body style. But, I'm no authority.
I had a '36 2 door where just the doors were steel the rest was wood. I been told that sedan del had wood in the back door till '53. Not sure if this is true.
...I had a 36 tudor that had virtually no wood in its construction. ...only in dome lite area and tack strips around windows.
Not including sedan delivery rear door, 1936 was the last year for wood frame construction. They did make about 2000 Standard 2dr sedans with all steel doors as a test before switching over for the '37 model year. There was one of these for sale at BTT50's about 2 years ago. You can get a reprint of the Fisher body manual for 1936 which talks about all of this. The '36 trucks had 2 different cabs, low and high. The high cabs were just like the '35 models with wood framing, but the low cab versions were like the later '37s. Not positive, but I think the low cab '36s were all steel.
I know this is a late addition, but GM (but not Chevy) continued to use wood in larger models like limos at least through 1938. I had a '38 Buick Model F (Formal Sedan with divider window) that had every bit as much wood as my '36 two door sedan.