The "frustrating" supplier was Jegs. I played the "ship back the old one and wait for another to come in stock" game with them once... only for the belated replacement to fail the same way. I since bought an aluminum radiator off eBay which is working great so far (but, the included "CNC" rad cap was way too high of a rated pressure, I didn't use it). I also had a liland global aluminum radiator from RockAuto that leaked a month after the warranty expired .
Summit is cool... nothing bad to say about them!
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V8 radiators are a lot easier to find than 300's (mirror images of each other, literally)... and usually a bit cheaper too. All new ones have automatic transmission coolers included from what I've seen. Just make sure you get the correct A/C/non-A/C that matches the shroud you pick out (the A/C version is more expensive but definitely the way to go, even if you're not running A/C). Speaking of which, the fan shroud will be the bigger deal to get right, but I'm not the first to say that.