I believe R-Vision used either the Velvac 2020 or 2025 back then, but not entirely sure. One place that's been recommended several times on this forum in the past and has had good reviews is Pacific RV Mirrors. I remember calling them years ago about a part/glass for a Velvac mirror and they were very helpful. Their prices are also lower than going through Velvac directly.
Not only do they have a database that can pinpoint (in most cases) the exact part that your manufacturer used as OEM but either have or can get almost any part for an RV mirror there might be.
Pacific RV Mirrors