I dont know if I'd feel comfortable buying a radiator off EBay. If theres anything wrong with it you have to pull it out and ship it back, the company you bought it from would either send it out to get repaired or send you another one. Either way your trucks going to down just that much longer while the radiators being repaired or in transit.
The seller I bought mine from was allnewparts, the brand was Cryomax, made in Taiwan. Not OEM quality but more than acceptable and only cost $70. You're call, I've had mine for 4 months without issues.
If you have a local supplier, see if they carry a brand called CSF. I have used them as replacements for OEM radiators. I like dealer parts quality, but many do not supply OEM radiators or the price for one is outrageous.
Radiator on e-bay...no thank you..the downtime not worth the $$ saved (if at all)..People may cringe when I suggest this, but my local NAPA store has always come through..Make sure to order the premium version, not the Mickey Mouse one. Premium will come through with all fittings if needed and will line up perfectly, the other will be a PIA.