i just had my tranny fluid changed. so i went home and put in some new shifter bushings. i look down inito the shifter housing and it looked like the fluid up there was still brownish and dirty. does the two fluids mix or are they sealed off from one another?

 

The extension housing is separate from the rest of the tranmission.
Clean the little chamber to get any old bushing debris out & add new gear lube.

 

holy cow, what a difference. the shifting is extremely accurate.used valvoline 85-140w synthetic. thanks!