I had the exact same drama when i ordered all the brakes for my 49 gmc 150. I checked a bunch of other places and noticed wheel cylinders were listed different for 3/4 tons but then when i called JC they never even asked. I actually asked them and they said they didn’t have anything different listed. I was all worried about it but after a while I decided to just roll with it because i was still moving forward with all the other stuff and i put it all together with the dual master and it all works flawlessly. It actually stops way better than i hoped for. So moral of the story is..... i dont know. BUT the stuff JC sold me is in and working perfect.
