you dont have to worry about a cel on that early of a truck.
but just make sure b4 you do it. look and see where the last o2 sensor is. if its b4 all the cats you are fine if there is one after the cats you need a spark plug defouler or something like that someone else will chime in.
but if you dont have any o2 sensors after the cats you can punch them or remove them and not worry about a cel. i dont have cats on my 94