The vent pipe is missing from the transmission on the '74 Class C. The opening itself is clear of any debris. Using a mirror, I can see about 1" down and observe something like a metal plug although around the edges it seems to be open to the transmission. I'll try to take a picture. When the transmission is running, I don't feel any air coming out of the hole. Would that be as expected?
Jim

Son-in-law, Dan, aka mechanic extraordinaire, says the vent is only for situations when the fluid gets very hot and expands, forcing air out the vent tube. Normal operating temps would not create this situation. What do you say, Barthers? He isn't one yet--I just get him to work on mine.
Jim