I cleaned a set of injectors up that came from another intake that I had. I noticed that the set that was in the truck had a stem coming out of them and my spare set was flat with 4 tiny holes in it. I put them in my truck and they worked fine. I'd like to know if there is any other major differences in them. I noticed that the intake I took them out of didn't have the threaded hole for the ACT. My truck is a 91 with a 5.0 E4OD