So if it has 4 wheel ABS, does that mean it has the upgraded rotors and calipers? For the diesel newbie, is there an easy way to tell the difference between the truck that has the changes and doesn't (take into account that I'm not used to looking at either model)? I just want to know what I'm looking at when I start truck shopping. I've found a couple of 99's but I was wondering if I should shy away from a '99 and go with at least a 2000 or newer that I know should have all the changes (or are they not that big of a deal)?
IIRC, when they added front ABS to the rear ABS on early 99's, an "exciter ring" was added to the front hubs. It is the exciter ring movement that the ABS sensor dectects when the wheel is turning.
You can see it between the inner & outer bearings in this picture of a desected front hub bearing. It's the shiney thing in the middle.
When they added the exciter ring to the hub bearing, it moved everything outward about 1/8" (the width of the ring). But since the hub now stuck out further, the brake rotor no longer lined up with the caliper. So with the newer "ABS" hubs, along came a different brake rotor which too was about 1/8" different so it would again line up with the center of the caliper.
I don't know if front ABS became standard on 99.5 trucks, but the new hubs & rotors did.
The calipers are supposedly the same. Just the hubs & rotors changed.