I've just completed the 0411 (P01) ECM upgrade in my 2000 chevy blazer ZR2 with the 4.3L v6. I'm running the 12212156 OS. The swap went pretty well, except for a couple things that don't seem to be working correctly:

1) The PRND321 dash indicator lights are not working at all
2) The speedometer is off by about 200 RPM at idle and about 1000 RPM at 5000 RPM.

Are these issues normal? Any fix? I've tried changing the tach output resolution high/low but it only made the tachometer reading worse.