I am looking for recommendations to replace the original Harrison radiator which split a weld recently. I intend to keep and eventually repair the original, but would like to know if anyone had recommendations for a "bolt-in' replacement. The original 400 is cammed a bit and has a tendency to run on the warm side (as Pontiacs tend to do). Anyone? Thanks!

Cold Case.

http://www.firebirdcentral.com/1967_1969_COLD_CASE_Aluminum_Radiator_AT_p/rad-403.htm

Thanks oldskool!

Have your old one rebuild using a high efficiency core. Just need to find an old time radiator shop that still deals with brass units.

I agree with oldskool, COLD CASE . Just upgraded mine to it after talking to a number of Camaro owners last year at shows. They all swear by it.
Rebuilt motor in this winter & a Cold Case in front of it. I was running a little hot also & the style of the cold case is very close to OEM. When painted you have to look twice to notice it's not "correct"

I agree with RAMAIR68, in most cases it's better to rebuilt, reconditioned and not replace your important car components. 100% stock system has been working for 50 years.
Some after market items are very desirable (EFI for example) and therefore worthy of installing on your driver. You just have to be carefull that you don't change one thing and bugger up something else.

Copper and brass is still the best material for a 60's car. Aluminum is lighter and cheaper that copper.
https://www.copper.org/applications/automotive/radiators/no_flux_history.html

Heating problems can be caused by an number of things, if you replace the rad with a new one (new or old school rad), it could still over heat due a other failed component(s). The next thing the guys will sale you is a electric fan. That noise making piece of [censored] technology don't belong on your engine. No way the electric pulls air thru your rad better than a stock flex fan or clutch fan (properly installed).

Your 50+ year radiator has to be serviced once in a while. You don't just take em when they leak, they need to be cleaned as well (remove buildup).

Start buy taking your old stock rad in for service and go from there.

My pricy desert cooler radiator has the wrong size side tanks

Thanks for the input everyone. I bought a Cold Case for the time being. I am having a hard time finding a local shop I trust to repair the original. I will keep it and have it redone when I find a proper shop.