904/a500 question

I have a 904 to freshen up (probably over the winter) and an a500 before that. I recently did a 46re. There's upgrade parts I found for the 727/46re that don't seem to exist for the 904/a500.
I'm looking for an upgraded front servo for the smaller trans or 2 if possible.
There were a couple of choices for these parts for the big trans, but not for the smaller ones.
Even as far as the rear servo for the 904/500 all I can find is the center pin and the servo disc in 2 seperate components, where for the big trans there are a couple of choices out there... Cast, billet, etc.
But that's more than I can find for the 904 or 500 for the front servo. What gives
Why can't I find any better front servos for this trans?

About 4-5 years ago I rebuilt a newer version of the a 500, it was either a 42 or 44re. Both take the "904" pan/ pan gasket. It was in my 99 Dakota I had at the time. I didn't take the whole gear train out just went thru the OD and pulled the front apart just enough to get the clutch packs out. So I didn't do anything with the rear servo. But I know that I found an upgraded front servo for that series of trans and used it at the time. Why can't I find it now?