This is just a point of interest to anyone considering a Corvette servo for their transmission. For my last swap, I used the Corvette 2-4 servo and found the 1-2 shift quite firm (at least for my liking). The swap I'm doing now ('89 Cheyenne) I was just going to use the stock servo, with some minor Sonnax upgrades. I got a couple of ATSG manuals to guide me through the changes, and came across an interesting service notice about the harshness of the Corvette servo. Their recommendation was to use the servo from the 4L70E trans. All well and good, but that trans was only used for a couple of years before the 6 speed and 8 speed automatics were introduced. So I tried to find the 4L70e servo. Turned out to be almost as illusive as the dial speedometer for the '90-'91 trucks. To make a long story short (too late?), I found one. Actually found the speedometer too, but that's a story for another time. Here's some pics to show the difference (left to right, stock, 4l70E, Corvette)