The instrument cluster is actually fairly simple to remove and replace(10-15 minutes), You can probably find a used one for a reasonable price at a local wrecking yard, The light switch must be removed to get to a screw that is located behind it which is probably the hardest part of the remove/install, There are three wiring harnesses that plug into the back of the cluster , Check these to make sure that one has not come loose then move on to the cluster itself.
If your cluster is bad you will need one from a 97 model year, If you can not find one with a tach you can use one without a tach as they are interchangeable.
My truck is a 97 and came with the standard cluster without tachometer, I wanted a tach and bought a cluster from a wrecking yard and installed it and it works perfectly , You must get a cluster from a 1997 if your truck is a 97 , The 97 and 98 both have analog odometers and look identical but they do not interchange as the wiring harness are pinned slightly differently(oil pressure gauge & coolant temp gauge).
The replacement cluster will most likely have different mileage on the odometer and you can either leave it without changing it, You can put your old speedo/odometer in the new cluster or the easiest is to change the mileage on the replacement cluster to match the one you are replacing, To change the mileage you simply remove the clear plastic front cover and using two small flat screw drivers reset the mileage to that of your original odometer, Using one screwdriver to seperate the number cogged wheels and the other to turn the one you need to reset, repeat this on each digit you want to reset.
Just a reminder here that your trucks actual mileage is stored on your trucks computer so keep this in mind when changing the mileage.
The computer will not upgrade the reading on the replacement cluster but when you go to inspection and they plug your truck into their equipment it may show the actual mileage stored in the trucks computer and they may question any difference shown on the actual odometer so I would not recommend setting to lower than your actual miles on truck. I would also recommend getting and keeping the receipt for the replacement cluster