I have a 4.3 GL and the water temp gauge is not working or reads very low. I assume this is a Thermostat problem. So I'm thinking about changing the thermostat, but not sure of the procedure. Any step by step guide would be appreciated or what should I troubleshoot first before changing out the t-stat. Thanks

Well first you need test the gauge

to do that you want to find the sender on the motor, usally right next to the t-stat
turn the key on and ground out the sender
if it reads full, your gauge is ok

i might be your sender