15 year old CB and still going but don't know how long. Has 1/4" steel firebox with a 3/8 bottom no grate.
It's starting to look bad being years of burning. Looking at something with a little more meat, like the 1/2" fire box. Once the metal is hot it stays hot. I'll try to give you and example, I'm a welder and when you heat a piece of 1/4' steel and a 1/2" piece, the thicker piece will take a lot longer to cool down. Same will be the case in the firebox. Plus I know after a lot of years of burning the firebox starts to break down.
On my CB the 3/4" floor shows no signs of any wear, but the walls and top of the firebox don't look so good. Cleaning the ashes out about once a month isn't bad but a pain in the butt, you have hot coals, and ash coming out the door and you get a face full of ash and still get some hot coals with the ash. That's why I'm looking a a owb with an ash pan.