Frame size and fit
The 3BBR0000182368: Frame size 2xR10 tells you the mechanical footprint and bus-bar pattern. If the existing cabinet has a 2xR10 cutout and the existing drive is an ACS880-04XT, this drops in without re-drilling the gland plate. Show me the rating — the frame size is the lock-out/tag-out boundary: verify the incoming disconnect and bus work are rated for the same frame class before you pull the old unit.