I don't know the exact part#
I'll know probably tomorrow when it is supposed to be in.
As far as ignition or rev limiter all I know is its the one under the nose on the EX towards the very front of the frame.
I ordered a '00 xr250 part.
Make sure you don't order xr400 part it is totally different and costs about $300.00 more.

Rdogg
'99 400EX
#46 MHSCA
Renthal handlebars, DG nerfs, shockwears, headlight covers, holeshotXCTs, titan fastrekkers,
WB E-series exhaust, brushguards,
k&n filter, jet kit, 14 tooth front sprocket, cool stickers,
and the rev limiter cut-out when it comes in.