XR305240 Xray 3mm blades (for the older XRay T2, up to '007) should fit.
I actually used the 3.5mm ones from a T2'008 and sanded them down slowly so the pin hole remained in the centre - long job, but I'm cheap(!) and had them spare in the pit box.
I'm testing again this week in wet, and early next week in dry (hopefully), so will be able to dial-in a couple of setups. Will post when I get that done.
I'm also udpating our LapAnalysis system for the remaining Scottish Off-road rounds tonight, so you'll be able to compare my laptimes from rounds 1, 2 & 4, with Scotty's from all 4 rounds so far, and see the changes - I ran the ball diff in the 511 at rounds 1 & 2, missed 3 and ran the gear diff in round 4. Scotty has run the 502 at all rounds but TBF has been running the car a year less than me.
Results are at :
www.sorcinfo.org/results
LapAnalysis will be at :
www.lapanalysis.n-esystems.com
and there'll be a 2011 section for the Scottish Off-road there this evening (late on - give me time!)