The sweeping left and right first turn at Red Bud has been replaced by a 180 degree right hander for the MXoN.
The fast left first turn had caused some fast crashes in the past, and the new first turn may have been introduced to help reduce the high speed incidents.
See the new version below:
Check out the full layout of Red Bud for 2018 MXoN:
And compare with the track for the 2018 US National: