The Siren Board

This morning I checked EBay for any Model A's for sale and I came across this:
http://m.ebay.com/itm/360873966791?nav=SEARCH
Do you think this could be the predecessor of the Model L?

That's the Vertical-Mount Model A. It's a normal Model A with the mount in the intake instead of on the motor cover. The Model L also had a Vertical mounting option.

To my knowledge, the Model A came before the L, D, and J. Don't quote me on that because I don't know if it is correct information.