As noted in the make by RC_Showdown, the original design does not take into account the fact that the bolts for the shock mounts are offset from vertical. I therefore revised the design so that the upper surfaces at each end are suitably angled. The greater thickness is easily compensated for by using the two 3x15mm BA3 bolts that are removed after mounting the rear gearbox assembly.

Creality

Ender 3 Pro

No

Yes

0.2mm

100%

Since the upper surface is no longer flat, I orientated the piece to put the lower edge of one end flat against the build plate and used supports.