I bought an after market transmission controller for a NAG1. It has the speed sensor on the output shaft of the transmission. Works great and I get 23mpg avg on the hiway!!! 5.7/NAG1 5 speed auto/2:76 gear in an 8 3/4 rear end.
Source soundgermanautomotive.com
You had a heck of a time getting it to work though didn't you? You also used a slipper driveshaft?
If someone could come out with a ready to go controller for a NAG1 it would be a great transmission for any muscle car. Your 2.76 ratio with a NAG is like a 727 with a 4.10 off the line
