Toyota Repair: Toyota Speed Sensor, toyota tacoma 4x4, vehicle speed sensor

Question
I have a 99 Toyota Tacoma 4x4, 2.7, automatic.  The speedomoter doesn't work and was advised by the Toyota tech that I need to replace the speed sensor.  I replaced the one in the crank shaft.  This did not fix the problem.  Also when braking, it feels as if someone is hitting from behind.  Could these two problems be related with the other sensor?  Any suggestions?

Answer
The vehicle speed sensor is located on the tailshaft of the transmission, is this the one that was replaced, if so and the problem still pesists the speedometer itself may have to be replaced.
The other concern is not related and in most cases lubricating all the grease fittings on the driveshaft and the rear slip joint on the driveshaft near the differential will take care of this.