Here is the reality check. Typing into Google or a video aggregator is fraught with risk. Most sites ranking for this term are not legitimate streaming platforms.
This list only scratches the surface. For a complete historical record, the is an invaluable resource, containing titles from pre-1988 retroactive ratings to the modern era. cat3movieus full
Because "Cat III" borders on pornography for some titles, many scam sites will serve you low-quality, unrelated adult content instead of the cult horror film you wanted. Here is the reality check