Bit of an involved process.
By design I left a gap between the inner driver outer flange and the interface with the girdle’s side plate.
I added (2) .60mm shims prior to tacking insitu the reach around to the strongback.
Opening up holes on the diff cover would reduce the effectiveness as a shear plate only relying on friction to keep the open end of the box true.
Install process:
A) set backlash with shims as normally without the influence of the girdle
B) remove the inner driver fasteners, leaving the shim stack in place.
C) add a stack of shims to the outside of the inner driver flange
D) slip the diff cover, gasket and girdle in place.
E) bitch and moan why it is so Fin tight
F) locate the diff cover fasteners and seat the cover
G) use a feeler gauge to check the gap if any between the girdle and inner driver fastener lands.
H) decide if you need to add shims
J) take the whole F thing apart to add the shim delta.
K) start from C and this time add thread sealant to the fasteners common to the inner driver if you are happy with the fitup.
L) pour your favorite beverage...
This is definitely not made for rally service time on race day. But again if the gearbox goes South it is swap the whole thing or game over.