Thanks for the information.
I got a new front rotor installed on my truck and learned a few things about Chevy 2WD fullsize trucks 1973-1987 .
First they use a hub and rotor assembly,it is all one piece,if you have a bad rotor you change it all,the rotor does not bolt on .
Second they only used 2 spindle and rotor conbinations,light duty with a 1 inch thick rotor.Heavy duty with 1 1/4 thick rotor.A heavy duty rotor will not work on a light duty spindle,it is a little to wide,the cottor pin hole in spindle will be covered.A light duty rotor will not work on a heavy duty spindle,it is to narrow and spindle nut will go in to far.
The brake pads will interchange .
This is the info I got and when I found a light duty rotor ,it fit.
I have several parts trucks and they all had heavy duty,mine was light duty,so I just got a new one.
Guess that is the way it goes,you never have what you need.And if you toss something ,you will need it tomorrow.