PS and ALT belts

Belts: (PS, AC, alt) Gates K050370 Alt. K040345 PS & AC

So I went to cdn tire and napa, and they had no idea what these part numbers were.

I can home later, and realized Gates was the name of the company that made the belts

with that particular part number.

So my question is, what part number or model/year should i be asking cdn tire or napa,

I m looking for a ps belt and alt belt for a s13 sr20.

I know that Canadian tire or Partsource carries two types of belts, Goodyear GatorBack and the torque belts:

Goodyear part no.
Alt - 4050370
PS & AC - 4030342 or 4030347 its plus or minus .2Iof an inch inner diameter from the gates K040345 Belt

Can anyone else shed some light or confirm?

I`ve been working at PartSource for the last 5 years and im positive those numbers are right.
the way you read the gates numbers K050370 and K040345 is the first 2 numbers tell you the grooves, and the last 3 numbers tells you circumference in inches…
ie. K050370 is 5 groove 37.0 inches in circumference

The explanation of what the numbers mean really helps, thanks. Now i can explain to the parts ppl what im looking for.

Thanks