3406b 4mg belt part numbers

New to the site but have been reading and using advice from you guys for a while now about fixing my b and boosting the performanc. I do all of my own work except for brake work. I currently need part/belt numbers for my cat as I am about to replace the air conditioning system because of a seizing ac compressor. Both sets of belts that are routed around the ac compressor/alternator and the crankshaft/fan drive are becoming brittle and I can not find any part numbers on these belts anywhere. It is a 2 groove ac compressor and alternator system if that makes any difference. My truck is a 1989 Pete 379EXHD 15spd with gears turned around, 3406b 4MG31204 425hp-pushing quite a bit more than 425hp in it's current state. I sure do appreciate any all help in advance.

 

That's funny that you say to use my serial number because today when I called triple t (closest truck shop), they said they couldn't help me without the belt number. I thought that was a little odd. I don't have the belts off yet as I just started the task around midday today along with additional maintenance. I will be calling pete first thing in the morning which is what I should have done from the get go. Anyhow, no biggie and I sure do appreciate the quick response.

 

Triple T in Wilmington, NC.

 

What's going on aktundratugger...I sure do appreciate that part number. I picked up both sets of belts today.