David. A very good site for scale drawings is "The-blueprints.com".
Loads of DUKWs there.
What is the end goal of these plans??? A static large scale model? floating /prop driven only or full wheel driven/articulate and prop affair?
Its a bit of a gamble, but if the x-list plan is for a floating prop driven model then this would be an adequate base for construction, using other reference material to detail the model. I cant see there is any right or wrong way to detail a DUKW…it was a truck and surely no two can have been the same after a while. There were differences in basic construction concerning the skinning and amount of wheel cover (I think) but again other reference material can be used to build the version you want, modifying the basic X-plan.
If it is wheel driven then its a whole different ball game and the generic you would be on your own with regards to the mechanics.
There are other considerations to making a floating wheeled vehicle, and that is a source of suitable wheels. Most important especially if powering them is the aim. In fact, the first thing i would look for is wheels.
The Alvis had been on my list for years, but only came to fruition after I saw some wheels.
Ashley