Is it my imagination or did some engines have aluminium bearings (perhaps not Lancias) or did some aluminium Aprilia rods run direct on the crank?
V12 Lagonda designed by WO Bentley had direct running alloy rods.
I just looked at a spare rod for my vintage Salmson - the white metal is 3mm thick. I does tend to crack after about 50,000 miles - mainly the edge which overlaps the side of the rod, rather than the running surface.
Mike