Here is what the read-me has to say about it being based on CFS3...
Junkers Ju88 A-14, KG77 Sicily 1941/42 by K. Malinowski and J. McDaniel. For FS2002. Based on stock CFS3 visual models. Many animated features, custom textures, custom flight model, full IFR panel.
This is what is in the installation instructions...
These visual models were adapted from CFS3 visual models and converted for use with FS2002/CFS2.
Visual model by Krzysztof Malinowski using a stock CFS3 model as a basis. Textures by K. Malinowski. Flight model and panel by Jay McDaniel.
Now it looks to me like they only used CFS3 as a visual basis for the plane. If that is true, they did a fantastic job because except for the cannon, this thing surpasses the CFS3 version by a mile. The fact that he says the plane is intended for FS2002 is pretty much a tip off too, in that it would have been pretty early in the CFS3 run that this plane appeared. The earliest listed entry in the download stats page is June 03. That is,I believe, before the aircraft sdk came out, so I doubt he would have been able to use the texture files from CFS3 as they are totally different.