Just got a 1990 Crew cab, 5.8, 2wd. Pretty good shape. Needs exhuast help. The ypipes come down around the motor, then they were cut off, and two pipes were welded back to dual mufflers. I am assuming that the two pipes should come back together and connect to a single inlet cat, then back to a single muffler. Anyways, the cat is not there. The AIR tube is, but I don't see a O2 sensor. Where is it located? These trucks have a problem with cracked manifolds, right? This has an exhaust leak, and has a noticeable stumble at idle and Take off. Any ideas of where to start? Thanks, will be a project truck!

Luke

 

If its anything like my 94 5.8 the o2 sensor it located straight down on top of the pipes between the two about 18 " from the bends at the front on the flat section. The pipes stop at a flange. They never join into 1 pipe. Then the converter is flanged and is a 2 in one out type. What i did was make a flange to match the y pipe flange and ran my duals from there back.