I installed a 20" cold case radiator on my '68 coupe. I noticed the cap was letting antifreeze leak out, as well as steam, which was weird since the temp gauge doesn't get above 195. After a closer look, I found, that the paint under the hood where the radiator cap sits is getting worn down, the radiator cap is rubbing against the underside of the hood. I put a piece of tape on the area and sure enough, when I closed the hood and opened it back up the tape was torn up. So, the hood, when closed, presses against the radiator cap. I measured the height of the radiator neck, it's 1-1/8", compared to the height of the one on my old radiator which as about 7/8". Has anyone else had this problem? I can't lower the radiator without elongating the radiator mounting holes, and that'll put the petcock so close to the frame support that I won't be able to open it. Also, this neck seems too long for most radiator caps, the one that shipped with the cold case is about 1/4" longer in the sprung seal than every other cap I have. I purchased the radiator from NPD, 8005-3EA, which is supposed to fit my application. Anyone else out there used the cold case?