All kinds of ?

Just got what I think is a lg bge from my father-in-law. It looks like one but it isn't glossy, it has a flat finish to it. The cast iron top is also not the same. It only has one slid not the two like I have seen on the net. He didn't know what it was and said he got it as a gift but didn't know when he got it. It been sitting in his pole barn for years. I told him what it was and he gave it to me( yes very lucky!). It was in a plain cardboard box. The only reason why I knew what it was was because a friends dad had one. I pulled the boxapart and all the parts were there but the gasket was kind of mess up. I put it togeather and took it up north to the cabin to see if I could smoke a pork butt. Turned out better then I hoped for consitering had no plan. All we did was throw it in the back of the truck, stop at a wallmart and got butt and some famous Daves rub. So after lookin at the web started the lump with some paper from the bottom and had no truble at all. Walked away for alittle bit and it got up to 650. Shut all the vents down and lifted the lid all the way open to get rid of some of the heatand the temp droped down real nice. Could not beleve how easy it was to keep the temp between 225-275. Had it on for about 7 hours. Took it of and put a metal bowl over it for an hour. Turned out real nice. But my ? is after the bge cooled down I looked in and my fire box crack into like three or for big chunks. The ring also broke. What did I do wrong? What should I do before I get a new one? Should I even get a new one. I can still use it now but I don't know for how long. Thanks