Found the yoke/chassis combination info on KLOV. I came across the same problem when. I bought a spare chassis for my Millipede, repaired it except for the foldover issue.
See if this helps:
3 versions:
"Latest" version had Vertical Dampening pot and a Vertical Position circuit board attached to the main board. (-040 confirmed below)
-040 , -055, -057
Yoke: 2021111258 or 2021111264
"Intermediate" version had a Vertical Dampening pot and NO vertical position circuit board.
-034 , -037
Yoke: 2021111258 or 2021111264
"Early" version did not have either a vertical dampening pot or a vertical position board. (Confirmed Below)
-023
Yoke: 2021111194 or 2021111201
"The early version is not compatible with either the Intermediate or latest versions due to the yoke being slightly different. If you use an early chassis on either one of the later ones, you'll get a foldover you can't adjust out as stated in the bulletin."