Nothing of the sort. He's talking shift firmness, not the point at which it kicks down to passing gear, which is what the part throttle module affects.
As long as he's not using a lockup kit in a non-lockup trans. or vise versa the valve bodies are the same. The only thing different about 998's or 999's were they were made heavier duty (more clutch plates and 4 pinion planetary sets) and possibly had a lower gear set.
