I've also seen two different style starters in the 4.2's. The one in mine looks like the starter in the 4.0 and a friend of mine had one that had a larger starter in it. He also had similar issues and tried 2 different starters. He didn't know what year anything was for sure either. The guy he bought it from swaqpped the trans and who knows what. Your old starter was definitely bad? Did the starter they gave you look the same? Are your battery cables in top shape?
05' Grand Cherokee Limited, 2"OME lift