speedo works somedays only

[98rngrfx4]

i checked the speedo post and it didnt help me. i have a 98 ranger 4wd xlt. my speedo works prolly twice a week and only when i first start the truck and drive. when it does this it only works for about 5 miles then stops. my odometer works only when the speedo does also. i replaced the vss on the differential. no help. i lookd up the part thats on the transmission and autozone has 2 different parts for my model truck. ahhhhhh confused