Heater core question

['69Novajoe]

Hey guys, I'm in the process of switching out my heater core. I've done one many years ago and the current one started leaking a few years ago as well. Just my luck, right? Anyway, I had bought a new core a few years ago thinking I would replace it some day. That day has finally come! When I test fit the core it looks like the tubes are closer together than the one I've taken out? It's only about 1/8" but the clamp that holds it in the box might have to be "adjusted" to make it work. All the dimensions look to be right but I thought I'd ask if someone could decode the part number to make absolutely sure it's the right core. And, yeah, it's an older core but at least it's not made in China!!