I thought I had a misfire in my 99 F-350 with a 7.3, and it turns out I have a dead hole in my motor, and the way its bandaged together I decided to just find a used one (after I only put 4,000 miles on it since I bought it unfortunately). The production date is 4/98 and has the exhaust pressure valve. I've been looking online for one, but for the search criteria it has thru 12/6/98, from 12/7/98 without exhaust pressure valve, and from 12/7/98 with exhaust pressure valve. My question is should I look for one thru 12/6/98 or look for one from 12/7/98 with exhaust pressure valve? I dont know much about these variations so any help would be great. I have bad luck enough anyways with this truck so I'd hate to screw something else up with it.