Accessory Belt Replacement
Replaced the belts on my M1009 and M1008A1 with the following parts obtained from RockAuto:
Power Steering = Gatorback 15461
Driver's Alternator = Gatorback 15581
Passenger Alternator = Gatorback 15491
After the 15 minute run in, and use of the Gates 91107 KRIKIT Belt Tension Gauge to set the tension to approximately the specified 67 lbs., the remaining adjustment available on each bracket was about half for both trucks. This leaves plenty of room for future adjustments if required.
Tricks for installation (these belts may seem a little too tight before break in, but I did not need to do anything extreme to install).
Power steering - Slip the belt as far inboard as possible past the crank pulley. Then, slip the belt as far inboard past the PS pulley as possible. Slip the belt back onto the crank pulley, and with the PS bracket at full retraction slip the belt over the PS pulley. It will take a little persuasion. Use an appropriate tool to pull on the bracket for tension adjustments. Do not pry against the PS reservoir.
Drivers Alt. - Slip onto the crank pulley. Then, slip onto the alternator pulley. With the alternator fully retracted, slide the belt over the PS pulley.
Pass. Alt. - Remove the top locking bolt from the alternator. Slip the belt over the crank pulley. Then slip the belt over the alternator pulley. Replace the lock bolt.
Adjust the belts as specified in the technical manual. I was able to use the "adjustment" holes on the alternator brackets just fine. Just remember to pry as close to the front frame (pulley side) of the alternator as possible per the Delco-Remy manual.
Please post your results if you attempt this method.
All the best!