I will assume it’s similar to my ‘75, so I have a few pointers.
- it may have a press-on pulley (mine does), so you will need to borrow a puller and press from Autozone or other store. On my original pump it was so tight that it broke the edge off the pulley, so I had to buy a new Dorman pulley. The other choice is a bolt on pulley.
- mine uses a cradle-shaped bracket, and at least one bolt is inaccessible until you remove the pulley. I believe there are two bolts holding the pump.
- newer pumps switched from SAE to metric on the pressure fitting, but I don’t know which year. You can adapt one to the other, but may need a new pressure hose.
- on my A/C truck I believe the hold down bolt for the tensioner PS is on the same bracket the A6 A/C compressor. Sometimes the PO has removed the factory compressor mounts and managed to screw up the threads and/or the tensioner for the PS.
- my truck had factory A/C with HD cooling. This means it has a longer PS belt that goes around both the crank pulley and the water pump pulley. Standard cooling uses a shorter belt that only goes around the crank and the PS pump. The advantage of the longer PS belt is that if your alternator belt breaks, the long PS belt will continue to drive the water pump and it won’t overheat.
- the GM procedure for getting air out of the system after you replace the pump is a little time consuming. You jack up the truck so both front wheels are off the ground, and then start the engine and turn the steering wheel full lock to lock 10 times. It sounds a little crazy, but definitely works.