Ok I did some digging, and found this ebay listing for trex 450 pinions. These say they are 48Pitch as well. with 3.17mm shaft diameter. Which is the same as what I got from LHS.
Anyone here more knowledgable about pinion gear pitch? If I can confirm for sure I have the right pinion, then I will just keep puttering with adjusting it, but if I definately have the wrong pinion gear I can hit LHS on the way home from work tonight and see what they have to say.