Ok guys. I'm sure there are plenty of threads like this but probably not my particular situation. Bought a 98 k1500 with a pretty bad body (tons of Bondo). Found a 98 c1500 with a great donor body. Swapped body from c1500 over to k1500 frame. With the k1500 ecu truck starts but dies. I know it sounds like passlock but the security light doesn't illuminate on either gauge cluster. I read about a chip in a grey box under the dash. Swapped those and still nothing. Tried the relearn twice....still nothing. With the c 1500 ecu truck runs rough (multiple misfire code). What gets me is with the c, the gas gauge doesn't work. With the k it does. Are these ecus pinned differently? Any help would be appreciated.