Try NAPA, they seem to have everything. They had in stock the 67 Torqueflite filter I needed for my GM trans. Autozone also had what I needed. Take the filter into the store with you. The number may not be good any longer but they might be able to match it up for you.
I was only kidding. The last year this filter was used was in 1967. After that they went to the thinner paper style filter with the plastic pick up tube. I actually checked around for this filter for the heck of it and noone seems to be able to get this style filter anymore. Seems alot more durable then the thin paper filter. Kinda makes me wonder when the last trans service was ever performed on the trans. Clutches where not to bad considering the Trans is from 67 and appears to have never been rebuilt. Last pic actually shows color of trans fluid from the trans running out of the pick up.