I just happen to have a 1987 Sales Brochure. The models are all Commanche and the layout comes with an identifying number, like the 395VS which is the top of the line outboard at 20'1" x 90" beam, down to the 320V at 15'10" and 78" beam. They offered 1 I/O the 395V (not VS).
Then they have a Rawhide (with none of the normal numbering scheme) at 15' x 73 3/4" beam. Then the Fisherman series which is a Walleye type fishing layout with a bass boat hull (has a pad and setback)...I had one of those but 1989 Model.
Don't know about just what the SN tells you. You could contact Ranger builders who are the Wood Mfgr. Co., Flippin, Arkansas 72634 (501) 453-2222.
You measure the length and beam with a top picture of the layout and I'll tell you what model you have....wondering why the name and model aren't just below the gunwale at the stern on the one in question...like "Ranger 375V" for a model?