What am I gonna do with these?

More info:

Yes, they were made in Australia (still don't know when or by whom) and will fit at least '63-'69 (and possibly also '60-'62) A-bodies with RH-drive, also trucks and vans. Likely also B- and/or C-bodies, not confirmed. LH-drive A-bodies such as we have in North America, probably not (collectors look to be right on target to hit the steering box).

Primary pipes are 1½". Rectangular flange ports are ~1.128" × 1.388". Collector OD is 2½". Tube wall thickness is 0.069" (which is between 15ga and 16ga).

Front collector has a small dent, see photos. Easy with a ball peen hammer, even easier with a pipe expander.

Rear collector for some strange reason is swaged to something a bit smaller than the collector's basic 2½" OD. A connector adaptor could easily be slipped over these and welded to the pipes, then about ½" sliced off the collector to undo this OD reduction.