Outer Limits 4x4 Board

Does anybody know , for engineers , do they require a self centering bucket style hole for the body mount rubbers?
Or can you just use rubbers and a center tube spacer in a flat normal hole?
Larry.

I hope not. Those poxy things rust out heaps easy.

I had the ones on the 2 outriggers under the firewall almost to the point where the rubbers were pushing thru the chassis. Plated 'em up with 3mm gal but i would make the hole big enough to re-use the crush sleeve to save the bolt from shearing (no sheep involved)