Someone mentioned RW do them now.
http://www.rccarshop.co.uk/index.php...-xray-xb4.html
I'm still running an associated spur (actually it's probably a kimbrough spur) for B4. You need to drill it out by about 1mm. If you dont have a drillpress, use a reamer and do it SLOWLY. you don't want to decentre it.