i've always figured the chips were part of the extra crap that GM was doing related to obd-ii level emissions testing experiments on corvette owners (that's why they have a rear o2 and why all EE bins have a huge datastream message with obd-ii parameters in it) although i have no hard evidence of that and haven't pulled apart a 1333 ecm myself

one thing to realize when you're swapping 1333 for 8051 ecms back and forth and trying to flash them is that the 1333 does not act as a bus master (it expects a CCM) so if you throw it into an fbody there will be no bus master. flashhack should deal with that just fine. if you put an 8051 into a 'vette with a ccm then both the ecm and ccm will probably want to be bus master, and i'm not sure that would work out well, so it might be best to yank the fuse for the ccm until you've flashed a y-body bin on it