Balls and plates in the diff are the same as for the gear itself im not sure, although i used the bfast xxx diff rings and balls in my xx no problems
A quick search online has shown the xx diff gear number to be the same as the BK2 buggy so its likely to be a straight swap
http://www.losipartshouse.com/servle...f-Gear,/Detail
Most parts are quite easy to get online, apart from the gearbox case and "X" chassis brace it seems
If you dont have a manual for her get it from here
http://www.vintagelosi.com/Manuals.html
The CR kinwald manual is good to download as it has Brians setup tips on it
Overall a very good buggy and I like em alot
Good luck racing her!