Here's what I got. Mazda Rx7 E38/No TCM with 07 Tahoe OS and harness. 5.3/TH400 setup.

Since I have no TCM I have no speed signal sensor for idle adapts or coast down adapts. Can I just select Manual in the transmission side of the tune and pin a speed signal into the PCM Terminals 71/72 VSS high/low? or should I reflash the PCM with a LS3 6speed tune and pin the pcm with a speed signal?

I had a 3rd gen 5.3/th350 swap in an s10 with no speed signal sensor I was tuning for a friend and on deccel the STIT would go way negative and want to die coming to quick stops for trying to bring the idle down while rolling. I disabled all idle adapts in that tune to get around that problem cause it wasn't my vehicle and I wasn't about to go through all the extra work to try and pin a speed signal in for free labor.