SN7404: No Lead E4 versus GREEN G4

We have been buying CMOS Logic parts for many years, but recently we have built products with "G4 green parts"  relative to "E4 no-lead parts" and we find that the G4 parts do not pass our tests while the E4 parts do pass.  We want to know how to order only E4 so as to never receive G4 which FAIL product testing?  Specific part is SN74HC04N and CD74HC04E.  Only E4 pass product tests (product is an RS485 Repeater that was designed over 30 years ago).  If G4 parts are used, it fails at the lower baud rates like 1200 baud, E4 parts pass consistently at all baud rates.