You'll have to replace the generic files that are included in the download. Replace the generic files to gtasanandreas/models/generic. It will not screw your txd up.
KNOWN BUGS: The GMC truck (Rescue truck) has a door bug. If you look on it from a distance you'll see a dispersing door.
This will get fixed in the 2.0 version.
My other mods:
Looking good Boo!
How is that Tanker coming along Boo?
I've canceled it, going to re-start on it when i have the time.