I have started working on an OBD2 LT1 XDF for use in TunerPro. I know I'm not the first, and I'm looking for anyone interested in helping or contributing. I've made a lot of progress with the big tables using commercially available hex comparison software but the individual flags and scalars are going to take some time and may require looking into the disassembly.

If you're interested, send me a PM. I can teach you.