Give the folks at Matto Cycle a call. (570) 429-0678
They helped me get all the parts to rebuild the bottom end
of my 1998 EC250. I would assume the crank, seals etc...
are the same.
I also have a .pdf of the parts diagram and numbers for the
1998 GasGas motor.
Send me an email address and I will forward you the file.
Steve Marolda from MotoWest (714) 562-3234 used to sell
and work on the GasGas MC and EC bikes. He might be a
resource for information. He no longer sells GG bikes, but, might
do work on them.
Jim Cook, Smackover Motorsports, also out of business, is an
old time GasGas guy. He still posts here from time to time.
I think I remember the MC250 was a 4 speed?
Good luck. Jeff