['ol Pinion head]

The most common disc brake changeover used on '64-72 A-body's is the '69-72 single piston caliper factory disc swap. That factory setup, have put together & sold over a 140 changeovers. It is basically what the chinese cheap disc changeovers are patterned off of, sometimes with no quality fit issues.

For 1969 GM models all 14x6 wheels were designed to fit both drum & disc A-bodys. As one examines 14x6 standard steel wheels from '69-77 GM A-bodys, they don't differ much in design. The back space from the hub mtg area to the back of the rim will typically measure in the 4 5/16 - 4 3/8" range.

Once GM began building the downsized '78 model A body (eventual G-body), the 14" wheel design changed. On a 14x6 standard steel wheel like an '81 model IL coded 14x6, the back space will measure 3 9/16". Basically that design makes the later 14x6 a zero offset wheel. Easy to spot visually. As far as S10's go, when introduced in '82 they used suspension pieces from the G-body parts bin. Going down the base S10 14" wheel route, I'd definitely measure backspace.

Where does this leave us? Not all 14x6 GM 4 3/4 bolt oattern steel wheels are even closely the same. IF one is trying to match what they have in a 14x6 steel wheel, one really need to note what one has currently has on the vehicle or for the vehicle.

Having quickly ID'ed by two letter code (or examined by quick glance) literally 10's of thousands of GM 14" steel wheels, can relay all above. Also, having sourced parts from multiple 100's of Auto salvages & old school wheel & tire shops, the days of going through the phone book, or a quick Internet listing, LOL, of Auto Salvages for a large metro are & finding a mainstream yard that actually has '69-77 usage 14x6 gm wheels, very slim chance of success. Unless the yard is a specialty yard or a very long time yard that next to never crushes, just not that simple a find. Even old school long time tire & wheel shops that have only sold through point of sale means, eventually, the owners scrap certain stock.