vin letter denotes brake capacity whats the difference?

[85-m1028]

I noticed that the m1008 has a G in the vin (1gcGd) which means it has a 8-9000 pound hydraulic brake system! But the m1028 has an H (1gcHd) which means it has a 9-10,000 pound brake cappacity, I want to know whats different between the 1008 and 1028 to add the extra 1000 LBS. of stopping cappacity??????? http://www.chuckschevytruckpages.com/81-87VIN.html see here for more info on vins

 

[ida34]

Larger brake rotors and calipers. larger brake drums and wheel cylinders. Larger master cylinder and most likely an upgraded hydroboost unit but I am not sure about this one. Mostly it is the larger size of brakes with the larger surface area for the larger friction material.

My F350 has a 12000 gvw with means it is actually a 3 ton truck not a 1 ton. The brake shoes for the duals is 3 inches wide instead of 2.5 inches wide for the non dually truck. This gives more braking power to stop the 12000 pounds of truck when fully loaded.

I don't know what specifically is the difference between the m1008 and the m1028 but it could also just be a paperwork upgrade on the brakes instead of any real difference.