Several days worth of head scratching netted the beginnings of what we see here (the backside of the core support). The biggest obstacle I faced was where to put the heat exchanger. It needs to be in the path of fresh air and someplace that's relatively easy to mount. Or you can mount it out of position and use electric fans. I opted for the first scenario, but it was easier said than done because the grille on the '68 is quite shallow, and I already had the A/C condenser in front of the radiator. There was plenty of room (81/2 inches) behind the radiator to move it back, which is what I did to make room for the heat exchanger.