FS9 model files can ruin your day, causing crashes of the sim, when loaded as a model to fly or worse, as AI traffic, just without warning somewhere when a traffic file is loading this file.
Install filesearch named "Everything" on your system. Let it build its database of your files.
Usually, you just can type in your search term with asteriks and the result will quickly been showed. This search goes into the file, therefore we need some more technique
FS9 .mdl files look like this:
FSX .mdl files like this
The difference is MDL8MDLH vs MDLXMDLH
There are more types, but you only need to recognize MDL8MDLH
To search this, open Everything, go into search, then extended search:
In the first field add *.mdl, let's only search models.
Next add the specific code for FS9 .mdl files MDL8MDLH in the fifth field. In the lowest field add the path to search. Click ok
It's working some time ... shown in the lower edge comment
After a while you get results:
The first result is astonishing. It is a converted Alpha C-141 Starlifter (P3D4) model. But the .mdl shown here is FS9. How does it come? Go into the directory and check the files. Right click on the file and select open directory to see it directly with other files there
So below are two converted models, exterior and interior, and also named FSX. The upper file is just the original FS9, left there for people who want to dig in deeper and modify something they need the original for. You can check model.cfg to make sure it is not called. If it was listed in the model.cfg, you could have problems when this model is loaded, usually a crash of the sim.
Regards
Dan