^^^ If you google "pickup frame rust" you will see that rust is problem at all cars, pickup, sport utility with frame instead of unibody. My Ford 99 has C channel and I use some rustproofing methods at it. From 2004 Ford switch to boxed frame and it is rusting badly. Toyota pickup at other hand rust even worse than Ford and GM. As I said spraying undercarriage work and I will keep doing it. My exhaust at pickup is without rust in 20 Mn winters. Only problem for me is I buy used cars/trucks so I need get it before rust get it.
I checked already my Acura and rust is minor at passenger side. I will do pipes redirection, it is not problem. As I said I'm rust fighting enthusiast and of course I checked for rust long time go. It is minor rust there. Only if I would know it is some rust problems at acura and Honda I would pull out my rattle cans of my gun belt earlier. In this neck of the woods rust do not stand chance.

 

I just discovered, after removing my right front wheel to do some brake work, that my front, rear beam has badly rusted, too. After doing some research to see if I could find a used piece, the rear/front beam (there are two separate beams, the front, "rear beam" is in front of the firewall, the the front, "front beam" is bolted from the rear beam extending to the bumper area. There is also a single "rear beam" for the rear suspension, so be careful how you search!). NOTE: For the '03 six-speed, there is a different REAR/front beam than is used for the automatic. I found front/front beams that were interchangeable with the later 90s Accords, but did not notice any front/REAR beams that indicated interchangeability. I suppose a 6-speed, 90s Accord might use the same one as a 6-speed Acura, but check this out carefully.

I hope that I've described this clearly enough, I'm using the Acura shop manual descriptions to describe these pieces, 'just trying to help anyone avoid ordering an incorrect part. I found a new part from a dealer in Delray, FL (Delray Acura) that had the front/rear beam for a six-speed at $636, which was a 31% discount from the MSRP.. I'll likely have to order this due to the scarcity of six-speed specific used parts. While I'm pretty adventurous mechanically, I'll probably have this done by my trusted, local shop. I'll do a rust preventative of some kind before installation(!), as well as re-routes for the AC condenser and sunroof drains.. These forums are wonderful resources,my thanks to all!

 

'Sorry, I didn't fully identify my car in the above post, it's a 2003 Acura CL-S, six-speed with navi, 236,000 miles.

 

Not sure about the 6 speed subframe being different but I don't have a service manual to confirm. Yes, the front, rear beam is typically what rusts due to the AC condensate draining onto it. Condensate is acidic and mix it with road salt or a salty, seaside community and you accelerate the rust. That's why eBay clean, used front subframe rear beams for around $200 + ship. My friend had one delivered and payed a local mechanic $1000 to install. Still a LOT cheaper than a dealer.