Ok, I have tested the GRFCodec program from J. Dexter website.
I was very happy to be able to edit the internal graphics of TT...
So, this does not help me so much.
I have also asked the question direct to J. Dexter.
I have questions concerning TT Manager. I have error messages at loading (looking for plugins) and trying to install/uninstall plugins does not allow to open files installed in the folder were is TT Manager
I though also TT manager gived the number of vehicles of the game

...
I attach two savedgames: one from me (fil transport, 167 trains, 52 road vehicles) and the other (multiplex that I had downloaded from your website and 'a little bit' modified : 147 trains, 13 road vehicles)
I hope you will find the networks interesting (thanks to Chris Doherty principles)
