Originally Posted by IanRTL
There has been a lot of discussion on this issue. It does appear that the washers in question could be replaced, but a suitable replacement part has not been located yet that I know of. The only other option is to replace the entire radiator as many have done - including me. I bought a Silla radiator that has brass and aluminum fittings so they will not rust. Others have purchased Koyorad or a similar brand. The radiator was $150 online and I took it to a dealership to have it installed. Total cost was a shade over $400. Pretty good insurance against a possible complete transmission failure. This isn't just limited to the RL or even just Honda, for that matter. The washers on the fittings of my old radiator were certainly rusted. They could have blown in a day or could have stayed together for several more years. I just didn't want to take the chance. I would highly suggest you follow a similar path if you plan to keep your truck for any substantial amount of time.
Is there a *known* good aftermarket radiator that can be used? I don't mind doing the swap proactively, but there isn't much information in the parts description of the different brands/models.