Thanks, guys, for hanging in there with me. It's been a lot longer slog than I imagined. I know you understand how relieved I was that the engine actually fired up on the first try. It's a big step forward for a LS newbie. Certainly not as ambitious as some of you who've transplanted donor engines and had to jump thru even more hoops to make it all work, but still a big moment.
I spent a half hour on the phone yesterday with a GMPP tech and he was very helpful, although at the end of the call I still didn't really understand the difference between the VSS +/- and speedout wires. My BIL, Rick, and I had a long conversation about pull up - pull down resistors and after the call, I stumbled across a line in the Classic Instruments manual that stated the tachometer signal needs at least an 8V reference level and to use a 1K ohm resistor if the input wire is coming from a PCM/ECU. I only had about a dozen loose resistors in my electronics box, but luck was with me and I had one that was exactly 1K. After connecting it between switched 12DC and the signal post, I have a working tach.
Now it's on to the speedo. The GM tech seemed to think that having the NAV system and the cruise control piggybacked off the same wire going to the digital interface box for the speedo might be attenuating the signal. So today I'll patch a wire directly from the GMPP harness to the speedo box to delete the other two sinks temporarily. If that doesn't work, I'll be on the phone to Classic Instruments on Monday.
I still have some work to do in the engine compartment, so it will be a little bit before I get the hood on. It's been leaning up against the back of the shop gathering dust since I brought it home from paint.