Films that, as far as I know, are currently unavailable in any format. Which hinders my desire to see them. Hopefully, the situation changes on these some day.
If anyone knows where I can locate any of these, please do speak up.
[Not included in list because of Letterboxd's stance on pornography:
Deep Sleep [uncut version] (1973, Alfred Sole)
Hard Candy [uncut version; softcore available on DVD as M 3-D] (1976, Stephen Gibson)]