The stock EB box is good. I have run it for the past 7 years with 33s. I just recently had it rebuilt by West Texas Offroad & they did an exceptional job. Another option is to do the 4x4x2 conversion. Basically you take a box off of a 78-79 4wd Bronco or F-150 & put the guts of a 2wd same years Bronco or F-150 into it. Look up West Coast Bronco, the store not the club, to find an entire how to write up on it. But the 4x4x2 box is stronger than the stock box. I will say that the only box that is a direct "bolt on" application is the EB swap. All of the others (Toyota, Scout, Nissan, 4x4x2) require a slight bit of modification to the mounting system. Personally, if I were going to go 38s or bigger, I might look into ram assisted. It is just easier on the box that way. Check out West Texas for that too. But any way you shake it, look at dropping right around a grand to get the conversion done.