Drop spindles and fitting disk brakes

[ChrisD]

Hi,
I‘m interested in these drop spindles: https://www.performanceonline.com/Western-Chassis-1973-87-chevy-gmc-c10-truck-2.5-drop-spindles/

But I‘m confused into this info:
„Fits original Heavy duty 1.25" disc brakes“
I don‘t know the difference between normal and heavy duty disk brakes.
Can someone explain me that?
I‘ve allready used google to find some infos, but i think i‘ve used the wrong words…

Thanks!
Chris

[LILT77]

There were two types of brakes. 1" and 1.25". These numbers are in regards to the thickness of the rotors. Many trucks came with heavy-duty 1.25" rotors. If you don't know what you have, just measure the thickness of the ones you have on. I have the same spindles on my truck.

[ChrisD]

Okay, thank you very much! 

Regards
Christian