I went a slightly different route and bought a ECB version without the grill as firebox. Then I ordered the ECB charcoal grill that normally comes with the Gourmet version of the ECB from Amazon. That way I got handles and the smoker legs and I did not have to build them as the fellow did in the link provided by SoaFung. That link was my inspiration to try doing a similar mod.
Everything went together just fine following the mod link, but I encountered serious air leaks. First, the side door had to be carefully bent to lessen leaks. The lip or top rim of the grill or firebox had to be straightened as it was not machined to be a flat surface. Finally, I had to use tape stove gasket around the top of the fire pan to get a decent seal. The seal or gasket went between the pan and the firebox and was affixed with stove dope to the lip of the fire pan. At night I used a light bulb hanging on an extension cord and slowly moved it around the outside lip of the firebox while looking down inside the barrel to try to spot air leaks. And I did the reverse and hung the light down in the smoker and crawled around the outside of the base of the smoker looking for air leaks...and I found the air leaks. It was a challenge closing off the air leaks. The tape gasket did help most of all. Finally, I laid down a layer of Saran Wrap on the barrel over the open side door and adding a bead of stove gasket dope around the lip of the side door then closed the door to get a good mating surface with the stove dope forming a good sealing surface for the door. The Saran Wrap burned off when I test fired the smoker.
Whatever else you do, do not follow the mod of installing four air dampers on the bottom of the fire pan you see on the mod site. The original hole in the base of the fire pan is plenty large enough. All you need to do is fabricate a sliding vent valve or damper control so you can control the air intake.
On the first test fire of the smoker the temperature shot up over 400 degrees real quick with the vent damper closed. As I closed off all the air leaks I got the smoker to finally cruise at 220 degrees. Getting the smoker to cruise at 220 on a hot day is quite a challenge. You will know you have closed off most of the leaks when you can get the smoker to work at 220 without the water pan. I was pleasantly surprised at how stable the smoker ran. It would hold a very steady temperature until the charcoal was totally consumed 12 hours later.
On the lid of the smoker I cut a 2 & 1/4 inch hole and installed a flag pole base mount I found at Home Depot. That was neat since it did not involve cutting four holes and using the Webber damper. Instead, I looked around and found a metal jar lid and secured the lid to the mount with a short section of light weight chain used with window blinds. That is all you need for the top vent as it will be open or closed. I have never needed to 'adjust' the exhaust vent for any kind of smoking/cooking activity with this smoker. Try to find that flag pole mount at Home Depot where the flags are displayed. It has been a year since I bought that mount. It makes the vent on the lid look very neat.
What is most surprising is just how small a burn is required to make a 220 degree burn. At night looking down through the top lid vent at the fire, (with the water pan removed), all I could see was just a very small area of the lump charcoal glowing. On warm days it takes very little air for the smoker to cruise at 220. The damper valve on the bottom of the fire pan was almost closed. You will need more air if you are using the smoker on winter nights.
One other thing I learned was how big a difference the evap rate of the water pan is against the rise in temperature from 210 and up. At 220 the water pan only needed some water added just once on a 12 hour burn. Run the smoker at 250 and the evap rate shot up very quickly. So, it does make a big difference in how long the smoker can run unattended before having to add water. At 220 the smoker could go almost 8 hours before adding water was needed....and I am not sure but that the smoker might have ran almost the whole 12 hours on one pan of water. You will want to find some kind of pan to sit the smoker on to catch the water the boils over if temps run high. Water running through the fire box will be black and nasty when it reaches the ground. I found a plastic stepping stone that when turned upside down would catch all the run off. A large flower pot base might work. Look around. Another mod was moving the water pan up two inches away from the fire. No reason for that water pan to ever boil over. I have not used this smoker in the dead of winter. Just assume you will not get that 12 hour burn on one load when the snow is flying. You can figure on a reload or two.
The temp gage that comes with the ECB is useless. A good long stem candy thermometer will work just fine.
Good luck with your smoker.