i was saying yes to terry's response. And as i said there is a size that is in between the 17mm hex for 1/8 buggy's, and the 12mm size for touring cars, This size is commonly used in monster trucks. It's about 14mm in size.
http://www2.towerhobbies.com/cgi-bin...?&I=LXFUG7&P=7
these all have a larger axle hole and axle pin, so it would be best to find the old ones.