if it was built in japan and just gave up
my guess was
previouse engine owner spun a bearing ( thought shit this will cost)
pulled off the sump replaced bearings put her back to gether running and sold her at the auctions
on tight arse jobs he probably just slapped teh bearings in and dindt torque it down properly
the 1000km later because the previouse owner didnt fix the actuall problem for the bearing failure you have had the same drama but obviously the dirver dint here the rattle before it was too late
if built in australia and is only fresh there are 1000 other reasons
pete