 HD features include full perimeter steel frame (there is debate as to whether the 9C1 Caprice uses a thicker frame than the civilian car; GM replacement frame part numbers for the civilian auto and the 9C1 Caprice are the same); oversized front and rear sway bars; full-size spare tire (in the case of the 4th generation 1994-96 Caprice Classic police car); high-output alternator; lifetime-rated green silicone coolant hoses; four-wheel disc brakes; HD steel wheels and speed-rated tires; quick-ratio power steering and transmission and power steering oil coolers; certified digital speedometer; stiffer body mounts and more of them; true dual exhaust; anti-stab steel plates in the front seat backs; performance 3.08 final drive ratio (3.23 w/std.