One of the first things I have to ask is what model transmission do you have in your truck? I'm going to go out on a limb here and assume that you have the 4R70W transmission in order to go on.
Your truck (if two wheel drive) likely has two sensors, the variable speed sensor (VSS) at the differential and the output shaft speed sensor (OSS) on the transmission tail shaft.
The OSS is used by the power train control module (PCM).
The VSS is used for the programmable speedometer/odometer module, or, PSOM as well as speed control and the ABS.
Assuming you have the correct VSS from the parts store then I would check to see if anything got in to the connector and that they are mated completely. Another thing to check would be the PSOM inside the differential as it may well be the issue if the speedometer/transmission were the issues that first led you to the VSS.
Mac
Your truck (if two wheel drive) likely has two sensors, the variable speed sensor (VSS) at the differential and the output shaft speed sensor (OSS) on the transmission tail shaft.
The OSS is used by the power train control module (PCM).
The VSS is used for the programmable speedometer/odometer module, or, PSOM as well as speed control and the ABS.
Assuming you have the correct VSS from the parts store then I would check to see if anything got in to the connector and that they are mated completely. Another thing to check would be the PSOM inside the differential as it may well be the issue if the speedometer/transmission were the issues that first led you to the VSS.
Mac