some pics of fhow thtee M05 changes it's wheelbase...
http://www.geocities.jp/hobby_show_a...a2009/0301.htm
swb - mwb Length
http://www.geocities.jp/hobby_show_a...a2009/0302.htm
all three
http://www.geocities.jp/hobby_show_a...a2009/0303.htm
mwb - lwb
Look closely, and it appears that the wheelbase is changed mainly by moving the rear arms. This goes in combination of moving the rear shock tower and body mounts (looks like three mounting positions on the chassis, and both shock tower and body mount bracket use the same mount)
For the swb, the arms are far forward as poss, with the body mount in the front mounting positions, and the shock tower in the middle one.
For the mwb, the arms appear to moved backwards, with the body mount in the middle mount, and the shock tower in the rear mount.
For the lwb, the arms are in the rear position, but also flipped. The shock mount off the front of the arm, and the body mount is in the rear mount, and the shock tower in the middle one...
So no more chassis spacers anymore...
Regards
Ed