Need to replace the wheel cylinders that came with the speedway 37-48 drum brake kit. In the Q&A section on the speedway site it says to use "1970's truck wheel cylinders". I'm sure i don't need to explain the problems with such vague information when talking to the local parts guy OR trying to search online. I've found some online that have the 7/16 x 20 inlet threads but i'm not sure of the bore size. Don't want to remove the existing ones to measure everything unless i have to. I'm hoping someone has some experience with this setup and or this request. The "tech" guy at speedway said to look for 1972 F150 2wd parts then said they sell them but gave me a speedway part number for a 37-48 Ford wheel cylinder, which makes sense because the brake kit is for 37-48 Ford other than that is not what is used in the application and will not work! Anyone have a part number for the proper wheel cylinder replacement?