OK, for the hard of thinking, I'll go over it again.
All Losi buggies use the same
front shock, no exceptions.
All XXX use the same
rear shock, no exceptions.
Pre XXX 2WD and all XX4 use the same rear shock.
XXX4 uses XX4 rear shocks.
Confirmed by looking on the Losi website.
XXX4-G+ uses 1.2" (XX4 rear) bodies and 1.0" (XXX) rear shafts.
The only thing you need from a BK2 over any other XXX is the CVD axle to allow more droop.