Why did light 3/4 tons / heavy half’s exist?

Ford, GM, and Dodge all had them. Seems like they peaked in the 90’s.

With fords, they usually have the 300 6 or the 351 and the semi floating rear axle, but still have 8 lugs. After the NBS came out they went to 7 lugs for some reason.

Chevrolets and GMC are badged 2500, but only have 6 lugs. Until the 2000’s, to be completely honest I still dont really know the difference between a 1500hd and a 2500hd gmt800.

Dodge, iirc the only way to really tell is by looking at the frame. But if it’s a regular cab 2500 with a V8, there is strong chance it’s a light duty.