im going to upgrade to 2.5r to pull start but was wondering if i could use this one? will it fit?
I really doubt it. Try to find a Traxxas one on eBay, I find them all the time for about $15. Remember that the 2.5, 2.5R, and 3.3 use the same starter, so don't be scared by the starter saying "TRX 2.5" on it.
You can buy the pull start from Towerhobbies, its the one made by Traxxas.
There is always ebay as well. They are going for around $10 shipped