Hey guys:
I've heard a lot about the vette servo being a good upgrade for a 700R4/4L60E.
My '91 RMW has about 120,000 miles on it and the trans appears to be fine, but I dislike the way it shifts. It shifts at the right times and all that but it has a nice soft, luxury car shift feel, and I would prefer it to shift firmer.
I actually bought a used 700R4 for my truck this past summer that came from a wrecked '92 RMS, and it did not shift as softly. With the TV cable adjusted for perfect shift timing, it had nice, positive shifts.
Also, I can tell you from experience that the VSS on a B-body 700 is not compatible with the ECM on a C/K series truck, and vice-versa. They use a totally different type of output signal.