Is the '98 Z28 LS1 ECU that different?

[0rion]

SD stands for Speed Density right? But what does OLSD stand for?

Open Loop Speed Density......no O2's and no MAF.

[N20LT4]

Open Loop Speed Density......no O2's and no MAF.

That's the way my tuner tuned my ECU - an Engine Management Systems 8860 unit, it's a open loop sys, no sensors. The '92-93 PCM is not the best.