74 d100 1/2 ton to 3/4 ton rotor

What all will I need to make this conversion? I am not trying to get increased spring rate here, just bigger rotors for braking when towing.

I know the inner bearing on the rotors are different. Are the spindles different sizes, or is the different size bearing due to the diff rotor?

Looks like they both use the same caliper but different caliper bracket.

There are 2 versions of a 3/4 ton pickup. The heavy duty version uses a lot of stuff (ball joints, spindles, tie rod ends) from a 1 ton and very little will exchange with your D100.
The lighter version is kind of a cross between a 1/2 ton and a 3/4 ton. It uses the 1/2 ton ball joints and tie rod ends, but bigger bearings (and I believe a longer spindle) to fit the 3/4 ton rotor. That one should exchange between the ball joints with your truck and the 8 lug rotor will fit.

That was what presented most problems with the Dodge trucks of the day. 2 guys would buy 3/4 ton Dodge pickups. Both guys could haul pretty much anything they wanted to without issues, but when it came time to replace parts, they could have had very different suspension and brake parts under the truck. The one ton stuff is about 2x the cost of the lighter duty 3/4 ton stuff, but until you looked under your truck, you never knew which chassis was under it. Gene

Same wheel bearings depending on year

My rule of thumb is 1/2" lug studs = Light duty
9/16" Heavy Duty
Same with the LCA's