I don't know how much this helps but my wife's A-518 (46 RH) went 228,000
before overhaul.  It had converter shudder and slipping under full throtle
towing (didn't tow much anyway and it's not hard to avoid full throttle
while towing) for about 30,000 miles before overhaul.  One day it flared on
an upshift and I overhauled it shortly afterward.  As to hard parts it was
in pretty fair shape, had to replace the converter and overdrive planetarys.