AR5 transmissions didn't have speed sensors unlike the R154's; I found this universal speed sensor kit that you can install on the driveshaft. Available in different diameters to suit the driveshaft's size. Could this be a solution? Speed on the tach may not be accurate but at least it is functioning.
Link:
http://shop.advanceautoparts.com/we...google&utm_campaign=value3&utm_content=value4
Diagram (different manufacturers):
http://www.powertraincontrolsolutions.com/download/db/Speed Sensor.pdf

You get the idea? Will it work?
Link:
http://shop.advanceautoparts.com/we...google&utm_campaign=value3&utm_content=value4
Diagram (different manufacturers):
http://www.powertraincontrolsolutions.com/download/db/Speed Sensor.pdf

You get the idea? Will it work?