Not a stop gap, an intended vehicle. The turret was also used on the LVT (A) 4 see the pic at
http://afvinteriors.hobbyvista.com/lvt(a)4/lvt(a)4.html (you will have to copy the URL and paste it into your browser as the brackets effect the direct link)
The kit is a reissue of the old Tamiya Kit and has the inherent incorrectly sized hull, simplified running gear and poor tracks. Still, it is a neat kit if you don't worry about those things.