Both tanks have codes that match the application (z/28 in this case). The pass side tank has a month code that should pre-date the build date. Both are very important to numbers match Z owners and need to be retained! Also the top and bottom support bars are very noticeable if they are not retained with the new core.
Most new cores have new support bars already installed and most local radiator shops don't mess with swapping the support bars, so you are left with a radiator that is worth significantly less then what you started with.
Also the tag soldered on the pass tank shows the part number and stamped number that needs to be retained. read about radiators here on CRG: CRG Research Report - 1967-69 Cooling Systems
Most new cores have new support bars already installed and most local radiator shops don't mess with swapping the support bars, so you are left with a radiator that is worth significantly less then what you started with.
Also the tag soldered on the pass tank shows the part number and stamped number that needs to be retained. read about radiators here on CRG: CRG Research Report - 1967-69 Cooling Systems
