Classic/Antique Car Repair: eletrical, blown fuses, fuse block

Question
i have recently purchased an 1991 dodge d-150. the engine and tranny have been replaced,everything works execpt for the speedometer. ihave checked the fuse block,and there are no blown fuses.the speed sensor has been replaced with a new one. i have changed the speedometer head and circut board from an local junk yard, with no results. i was  wondering if there was another set of fuses i dont know about. also the truck is an automatic now,if that makes a differance. thank you for your help in this matter

Answer
The speedometer is electronic in this truck. The speed sensor sends a signal to the engines operating computer. That signal is used to control the fuel mixture, spark timing, cruise control, transmission shift points, and the speedometer. The diagnosis for a speedometer problem is to get some one who has a scanner that will plug into the computer and read the computer output. It is very possible that there is a computer problem. If the computer is telling the scanner that it is receiving the signal from the sensor and giving output then the problem is wiring between the computer and speedometer or the speedometer. But the starting point is the scanner check of the computer.
Brad