Radiator Out-let Help for LS1 Plumbing

[badazz81z28]

Gents,

Running my LS1 crossover tube back to the radiator.

My radiator seems to have 2 possible threaded connections built in and both on the same side. Which one should I use? There is one right below the radiator cap, the threads look like 3/8" NPT and there's one about 6" below that which looks like 1/4" NPT....



Does it matter? The top one looks like its meant for a heater hose.

Thanks!