All of the spoked MPIIIs have 36 spokes, but you will have to be very careful that you obtain the correct length spokes to suit your particular rim.
If the rim you choose is not a deep "V" doubled walled rim it will probably require longer spokes than the standard GM rims.
Most wheel builders use specialised programs to calculate the required length of the spokes according to specific rim and hub dimensions.
Please note that none of these typically used programs are likely to be able to calculate the correct spoke length for the MPIII due to its unconventional spacing of the spoke holes around the hub flanges which was required in order to produce a more acceptable angle between the spokes and the rim.
You can use the
Spoke length calculator from ebikes.ca to find the correct spoke length, but Check out
this post for additional important information first.
Alan