Where are the up and down stream o2 sensors. i have replaced the one directly in front of the cat, but can not find the other one... thanks (v6 sr5 4wd)

That engine is OBDI and does not have a second HO2 sensor. They use the second sensor downstream of the Cat. Converter to monitor the Cat. Converter function in OBDII engines (1996 and later).

I believe 1994 trucks made for the California market have a second sensor after the cat. converter.

http://www.autoshop101.com/forms/h24.pdf