Technical Big Bore Calipers?

Need help to identify the calipers mounted on the drop front axle of my 30 Ford. Someone identified them as "Big Bore" calipers from 1988 to 2002 S10s. After checking, the mounting bolts on the S10 calipers are about 6 1/2 inches from center to center. The mounting pins on my calipers measure almost 8 inches from center to center. Any help would be appreciated. center to

 

Googling the casting# brings up a wide variety of GM vehicles; Buick, Cadillac, Olds, Chevy Suburban.. and on and on.

 

I believe the S-10 calipers would be the standard GM metric calipers. Those would have about
5-1/2" center. Back in the late '70s the GM big cars like Impala had a caliper with wider mounting holes. Those have about 7" center to center mounting bolts. Yous kinda look like the big Chevy.

 

I learned the hard way.....S-10 calipers 'need' shivel-lay master cylinders to work right.
Couple of HAMBers on here steered me the right direction on those type calipers.
6sally6

 

this is mid 1980s full size Chevy truck, sure looks like it, eh?

 

If you decide to use a GM METRIC CALIPER, they (most) are low-drag and requires a step bore/quick take-up MC. The MC piston would also have to be matched with the caliper piston size/swept area to operate properly.

 

One way to ensure getting GM metric calipers WITHOUT low drag seals is with NEW aftermarket calipers, like those from AFCO, available in three piston sizes, that use stock GM pads and hardware.
I credit HAMBers gimpyshotrods and Joel for learning about the alternative to buying rebuilt GM calipers, without worry about the low drag seal.

 

Full size GM Metric 77/ mid 70's probably up to the last rear wheel drive full sixe GM cars.
Click on the the Delco part number after you open the link and it tells you what it fits. ACDELCO 18FR623C Caliper | RockAuto
Below from Rock Auto's More info page.

It's just a GM metric "big" caliper as apposed to the GM Metric "small" caliper on G bodies.
They do fit 81/86 C 10 pickups. Making getting pads real simple.

 

Thanks for all your help. We were able to confirm that the calipers in question are for a 1969 to 1977 GMC midsize car.

 

Yep, looks identical Thanks

 

Yes, Exact same casting number. Thanks