The final Phantasm movie, Ravager was made slowly in the time between Phantasm: Oblivion and the passing of Angus Scrimm. Starting out as a series, it was eventually built upon until it was a movie... (blog post) or.. at the very least, a Phantasm movie. Also, this one isn't entirely the writing and directing of Don Coscarrelli, so mark it as the first time since Phantasm II that "outsiders" had a large sway in how things went down in the film.
Source: Phantasm: Ravager Movie Review - Decker Shado