7500 GVW vs 8800 GVW brake parts

[Oregon Ram]

I just picked up my 96 dodge ram 8800 GVW 2500 diesel 4wd from the shop today after they installed new rotors, calipers and pads. I noticed that the calipers listed on the invoice were 7500 GVW calipers. I questioned the shop about it and they said they ordered the 8800 parts originally but they had a hard time getting the calipers and pads onto the rotor. That the rotors were too thick, so they installed the 7500 parts. (I'm assuming 7500 rotors as well) . This does not make sense to me. How, (if the RIGHT parts were ordered and received from the parts house) could all the parts not fit. Any help would be appreciated. It doesn't make sense to put ( what I consider ) light duty brakes on a Heavy duty truck.

They also replaced the front wheel U joints as well as the hub and bearing assemblies on both sides. Now I'm wondering if they used the right parts for these parts as well.

 

[LorenStrodtman]

I can't offer much useful advice, but my 2 cents is that you have every reason to wonder about it and keep investigating.
Do you have brand names and part numbers for what was installed? Manufacturer online catalog should list the specs (thickness, area, etc.) for all of the parts - both what was installed and what SHOULD HAVE been installed.

A search on RockAuto.com for applicable right-hand caliper part numbers yielded FRC10183 for 8800 lbs, and FRC4413 for 7500 lbs. Going to Raybestos website, they show that the 8800 lb caliper is nearly 14 pounds, the 7500 lb caliper only 11.1 lbs! I have been unable to find the "behind the counter" type of catalog data, but only browsed a few minutes. Clearly that doesn't state WHY they couldn't get things to fit, but at least confirms that there's a problem.

Hopefully someone else can chime in to help, and I'll try again when I get some more time. These kinds of mysteries always pique my interest!

[Edit] The AC Delco rotors for the 8800 lb truck are just over a 1/4" thicker than the 7500 lb. Part number 18A558SD vs. 18A489SD. At this point, I see one possible cause is that 7500 calipers were put in a 8800 box when sent to your installer.