Ralphy, I am very sure there were no slots in either of my valve covers, since I was the one that stripped them to bare metal, degrunged the inside, and painted them. They were the 216 style with the acorn nuts holding them down on the top. The filler cap was at the front end toward the radiator. I no longer have them, or I would post a picture. The truck had a 1948 head with smaller spark plug holes for some reason, but the other engine had the original head and both blocks were 1949/50 casting numbers.
Being that I live in the Pacific Northwest where a lot of rain happens, maybe someone swapped them for non-slotted covers at some time or another, but I know that my truck came from an Iowa farm and was not messed with in the short time it spent in Oregon before I got it.
I have seen so many pictures of differant valve covers on differant year vehicles that I almost think it depended which plant made the vehicle on what cover it recieved.
The 1958 235 and the 1962 261 I have both have the same Chevrolet script 4-bolt cover with no slots and vented filler on the front.
