not to revive a dead thread (is it dead?) I have the square brinkmann box, and I can give an easy few suggestions for cheap. I took out the hanging rack for my firepan, and just set the firepan on the bottom of the unit. It's gets airflow from the vents, and didn't require any new parts for me.I never have problems with ash-choked fires anymore, and I stopped burning charcoal at all in it. I use wood. seasoned pecan and mesquite, I start small wood twigs and such in the pan, then set a pair of larger pieces (usually long enough to bridge the firepan) with an airspace between them. the logs themselves help moderate the temperature without me having to adjust the vents for the most part, and with the airspace running 'across' the smoker (from vent to vent) the coals don't suffer at all.
I do have the water pan, and since I use it for flavored steam (or to catch meat drippings for au jus) I swapped out the pan that was in to another one, a gallon capacity stainless steel mixing bowl, which has been a wonder and a joy to use. (as far as water pans go)
I've had this little monster for about 6 years, and I'm planning on upgrading soon, as I'm one that uses his equipment to death. I've replaced the thermometer with another one, which helped, but that was about a year in, and other than that I've made no mods. I figured this was always a bit of a 'throwaway', and that if I could learn to regulate a fire and regulate my temps in this thin, flimsy, leaky, semi-shoddy...
....the n I could learn to bbq anywhere. And since I've taken up wit this thing, I've learned how to do in clay pots, holes in the ground, a smokehouse...
Never underestimate what a clever man can do with simple tools, or what a simple man can do with clever tools (no offense to any of you grand pitmen who have very good equipment, btw) and when dealing with the...'cheaper' end of the spectrum, we have to be very creative and clever.
It's not a 'bad' box, and a good one to start training, but if you're like me, and smoke at least once a week, you start to feel a little restrained by it. I've developed a bit of a love-hate relationship with mine.
That being said, if you can learn in this box, which is fiddly for temp control and fire handling, you've got a couple of really good skills.
Good luck and congrats!