OldIHC

I agree, Lloyd!
California was told it was "targeting poor people" with its safety inspections. CA stopped them forty years ago.
Turns out we now use smog check to gently suggest other things get fixed. We are not always heard, though.
Smog is made up of HCs (unburned fuel) and Oxides of Nitrogen (NOX) in the presence of sunlight. This stew causes ozone to form. Ozone is just so tough on rubber, paint, people.
This chemical reaction doesn't care if it's in CA or Wyoming or Texas or Florida.
Automobiles and trucks are the number one cause of HCs and NOX in CA.

I had no idea that such things existed locally inexpensively:
This is a "set collar".
Exactly 1.25" ID and 2.00" inch OD
2.00" is correct for wheel seal ID. 1.25" is correct for spindle.
It may be a little wide. Still easier to deal with that than have two spacers made.
This "spacer" will push rotors outward a bit so nut and washer can properly preload bearings.
As a bonus, it looks as though caliper will fit between stock Studebaker wheel and rotor.

This thread is all over the place and I love it!

I "made" this late IHC Six Speed Special (1930?) into a tow truck using an old (heavy metal) curved tractor engine hoist (I sliced a pie section out to make it lean back). I then connected the curved boom to heavy plate that tied into the frame on both sides. I then attached a Little Giant winch securely to the bed.
It's for show, not go. Although the truck ran.

Got one rotor mocked up on the Stude spindle. I'm showing all parts numbers just in case it comes up here, again.
I had to use a sawzall to cut one set collar in half. Thinner is better here.

Texas has a rolling 25 year vehicle age limit. 25 years or older no more inspections if you register as a classic or antique. So this year 1991 and older qualify.

California STARTED the rolling exemption (you can imagine how often a smog tech like me gets asked this question). Governor Pete Wilson started it and Governor Gray Davis stopped it. It only got to move one year from 1975 to 1976. And there it sits! There is NO WAY we can find smog parts for this forty year old stuff.

Finally glued on modified 1.25" set collars on spindles. I then old-school packed the new wheel bearings by hand and slid the rotors on. I'm gonna call this a success. There appears to be plenty of room between the big rotors and the inside of the 1960s Studebaker pickup wheels for a caliper.
The Studebaker wheels fit great. Those of you that like wheels to center on the hub (like CB) will be disappointed. I'd have to find a piece of pipe or have a ring machined for that perfect fit. Until then, the lug nuts center the wheels on the rotors. Otherwise, a homerun!
Turner Brake (Stude Disc Brake Conversion Kits) wants something approaching $800 for this conversion.
So far I'm in it about $120. The veteran counterman George at Smith Auto Parts in Dinuba did all the heavy thinking and searching for this conversion.
Next, I'll buy the "universal" caliper brackets on Summit or Speedway and make my own brackets.
I've again shown all the parts I used, including the 1.25x2.00" set collar.
Stude pickup spindles are 1.25" and .75" big and little bearing ID. 5x5 bolt pattern.
Once again...I'm putting 1938 or so IHC D-2 cab on last series Stude 1/2 ton pickup frame and running gear. Stude pickup is different from Stude Car. Turner Brakes is the way to go if you don't want to think and don't mind paying.
All this trouble because I refused to use anything but the stock, cool, Stude wheels and caps...
It'll be the first IHC D-2 "S" version!

Just to clarify, I've been told this "one year" rotor is from a 1977 Buick full sized car, 5x5 bolt pattern. OK. I ordered and installed correct dust caps. Dorman part number as shown.

I have a set of brackets that I didn't use for a 57 chev conversion. Pay the freight and they are yours. If you send me a place to get you a picture I'll send one of those first.

I may take you up on that if the brackets I bought won't work, Blind Squirrel. Thanks!
Since I'm opportunistic I'll probably use the original backing plates as dust shields and lap weld the brackets I have on to that. Or not.
We will see.
Might happen this long weekend!