RatherBeFlying
WT, I am guessing the photos were mostly Ektachrome -- certainly faster than Kodachrome.
Large format transparencies are Ektachrome, whilst oblong ones are Kodachrome. Of the two I preferred Kodachrome, much less grainy and over the years they are as vivid and colourful as the day they were taken.
I've had all my (nearly 1,500) Kodachrome slides scanned professionally to digital format which makes printing and showing them a doddle.