[jhv48]

From what I’ve read, heard, and experienced, the problem with TKO 600 gearboxes is internal and should be addressed before upgrading the shifter.
In my case, I replaced my TKO’s stock shifter with a Steeda model and it made no difference in shift quality. Still shifted like a truck.
Finally bought a blueprinted trans and haven’t missed a 2-3 shift since then.
If you have the time and haven’t installed the trans yet, do a search here and take the trans to a specialist for blueprinting. That’s about the only way to smooth out a TKO. Then you can use any shifter you want.