Experimental CrashHard 8x8 BigRig Truck 1.1.6

Some bug fixes for the CrashHard 8x8 BigRig Truck.
- Fixed a lot of stresses in the J-beam, for the airfilters, exhaust, exhaust holders, the cargo floor, the cargo walls, the cab and all its parts.
- Fixed the RPMs for all the engines +lowered the power a bit (max rpms are now 3200)
- Fixed the locked diffs being to weak.
- Corrected some misspellings in the part selector.
- Made the front cab plate into a part you can remove in the part selector.
- Added a big weight to the rear for better balance when offroading (Find it under cargo upfits)
- Made some more variants that should be easier to run (Better fps)
- Added the seats back into the stripped versions (for the driver camera to work)