Older IHC 's were 1100 and the later model was a 1300.  Both are good.  I have a 9 ' now, and have had a 7 '.  There is a replaceable bronze bushing in the sickle had that should be replaced if any play is seen.  Also the 1 " dia pin that goes in that bushing should be replaced if it feels like it has some wear.  Neither is a big expense or problem.  As someone else said, keep sharp sickle and ledger plates in it.   Guard # MC 2041 Z is about $10 the last time I priced them.  Unsure of the parts prices for the other brands