I ordered the calibrator prom for 1982-84 lg4 part number 24502457 from GMPARTSDIRECT. It was burned for the special emissions prototype ho 350. The other prom available from the 10185077 conversion kit is 24502456 which matches the 1985-87 lg4 and the 1983-86 l69. I'm staying with the original ecm in my car. 1228079 is the ecm GM offers in all the engine types Through research and verification the computer is the 1987 lg4. The number however has been superceeded to 88999154. why? Perhaps change of manufactuer or improvement of function. Is the 87 offered faster because the the prom controls the program. I know the proms are different in somepart because of the knock sensor issue and possible vats. Any way when I get my 350 I think this chip should work better than a 305 Hypertech. RIGHT/

 

Im reading the zz4 chip ignores egr. If true what kind of problems will this create?