Start with a google site search (bottom of the search menu) for all Ventura-related posts. That should help you narrow down when they were made. Most molded trailers used the identical design across multiple years, though, so the best you can hope for is a range. You can also use the manufacturers tab at the top to locate
Ventura information. Some site features are only accessible from the full website, so if you’re using the mobile skin on a phone or tablet, scroll down to the bottom left corner to switch to the full website interface.
Depending on the age it may have a standard
VIN or just a manufacturer serial number. It it has a
VIN, the motor vehicle department can likely sort out the year. If not, post the serial number here, and other Ventura owners might be able to help narrow it down. They typically run in numerical sequence. Don’t expect an overwhelming response, though; it’s not a common model.
Either way, a physical or virtual visit to your motor vehicle office is in order. Find out what the process is for gaining legal ownership of an abandoned vehicle. Don’t put money into it until you get papers in your name.