Gamer!'s Ultimate Pickup Parts v1.15

MD-series — major update

This update expands the MD-series into the Class 8 US truck category, adding a huge number of new parts and fixes.

New parts and features:
- Tandem rear suspension (3 spring stiffness options, 2 ride heights, off-road springs)
- Lifted off-road tandem rear suspension
- Lift axle compatible with tandem and single rear suspension
- Adjustable rear single suspension (moves forward/back on the frame) — same for tandem
- Sleeper cabs (long and short) with matching front frames
- High roof single cab (compatible with sleeper cabs)
- Auxiliary support add-on (made from scratch): side toolboxes, rear fuel tanks, air tank mounts, headache rack, snorkels, adjustable frame length via tuning slider
- Heavy duty air compressor (for lift axle configs)
- XL rear frame — supports T-series 26ft box and flatbed upfits + special celebration skin for the box
- Rollback upfit (shortened from T-series, ~3/4 length)
- Side fuel tanks (3 lengths, movable along the frame)
- Hydraulic steering for off-road front suspension (no bump steer, stable at high lifts)
- New color options for late grille, headlight bezels, factory bumper (black, matte black, chrome)
- Updated exterior roll-cage + alternative cages (aligned with D-series options)
- Short 4WD transfer case (higher and further forward — more ground clearance, shorter rear driveshaft)
- Bigger race turbo, extreme race internals, 4200 RPM governor (for high-hp drag config)
- 3 new longer fifthwheel rear frame endings (more space for axles and fuel tanks)
- Fifthwheel attach helper for off-road ride heights (better ramp for trailer pin)
- Single center roof halogen beacon (amber, red, blue)
- Cut rear bumper for flatbed
- Mudflaps that move with the suspension
- Fixed-length rear driveshafts
- Long fenders for tanker upfit
- Long front left side step

General fixes for 0.39:
- All lights updated to the new lighting system
- All D-series diff locks updated with interior switches; 6x6 rear diff lock merged into rear diff lock; interaxle diff lock switch added
- D55 and race dashboard updated with new switches and sun visors
- Custom colors fixed for 0.39; 4 new colors added; many moved to custom
- All trigger boxes now show proper names
- D-series car hauler hydraulic ramps fixed (updated to powertrain hydros)
- Long rollback deck on D-series and H-series — extending fixed
- D55 air tank, fuel tank, bumper material — shading fixed
- D-series small trailer tongue texture fixed (was fully white)
- "Gamer" text removed from license plates on all configs

Configs: most reworked, many new — total now 43 configs.