1999 GMC 6 CYL Clutch
 

Hello my clutch pedal goes to the floor now for me the shift gears.I looked under the truck to adjust the clutch and there is no cable to adjust. How in the world can I adjust it ?

No can do. It has a Clutch Slave Cylinder system. Non adjustable. Just make sure your fluid is full for the clutch. With this system, when the clutch wears out overtime, the pedal will seem to also need more clutch to change gears. But if this is something that has just happened, then you could have air in the system, a leaking line, or just a bad slave cylinder.