Mystery II - V-Drives ID

[jgalt]

Here are the V-Drives on my project boat:

http://home.hiwaay.net/~rcleere/Yacht/pics_1/V-Drives_0164_sm.jpg

Walter V Drive, either RV10, RV20, RV30, RV40, or RV48

Anyone recognise the model from the pic? I have a 28' cruiser with a Bertram 28 style hull.