Quote Originally Posted by Chri$09 View Post
4L60E, 700R4, 4L80E, 4R100, E4OD, 2004R, C6, TH350, TH400 Transmission: SUPERIOR 700R4/4L60E BILLET SUPER SERVO 4TH APPLY PISTON AND COVER

AND

4L60E, 700R4, 4L80E, 4R100, E4OD, 2004R, C6, TH350, TH400 Transmission: SONNAX 700R4 4L60E 4TH GEAR BILLET SERVO

WHATS THE DIFFERENCE?
The difference is the degree of holding power. Both will firm up your 3-4 shift. The Superior Fairbanks is more extreme than the Sonnax and is usually more appropriate for the dragstrip. The Sonnax is a great in-between (between stock and Superior). Read about all the servos here.

I'm running both Sonnax servos with the Sonnax chromemoly servo pin and have no complaints. The Sonnax 2nd gear servo is a nice improvement over the Vette servo I was using before.