More than likely the squeal is from the speedometer. They are very easy to fix. In your case pull it from the truck and turn it so the cable fitting is up. Put a couple of drops of engine oil, I have been using Mobil 1 with 100% success.
Occasionally you need to disassemble the instrument and lube some of the other shafts in them but the squeal is the input bearing.
With the cable I use a "Marine Moly" grease from McMaster Carr. This is a very slipper light blend grease that works well especially up in the colder climates. An alternative to the Moly grease in the cable would again be a synthetic oil.