2003 F-350 7.3L

Looking for a replacement serpentine belt I came across this.
W/ HD Cooling and Exc HD Cooling.
What is HD Cooling?



GOODYEAR Part # 4081215 Gatorback; Poly-V; 8 Ribs / Effective Length 121.5" / Outside Length 122.25"
Poly-V; Single Alt, W/ HD Cooling; Accessory Drive
$28.79

GOODYEAR Part # 4081223F
Poly-V; Single Alt, Exc HD Cooling; Accessory Drive
$32.79

GOODYEAR Part # 4081223 Gatorback; 8 Ribs / Effective Length 122.375" / Outside Length 123"
Poly-V; Single Alt, Exc HD Cooling; Accessory Drive

 

Unsure of the term "HD cooling", but order the dual-alternator coolant hose while you're at it. Installing this allows you to swap the belt next time without removing the hose. Ignore my zip-tie, it's been trimmed.

 

Last time I replaced the belt I put in the "dual alternator" hose that goes around the belt. I checked the model number on the belt and it is the 4081223F. I have since learned that the 8 in the model number is the number of ribs, the 1223 is the length ( 1223 = 122.375") and the F denotes that the belt has aramid fiber in it.
Still not a clue about HD cooling, but from the part numbers, if I am using the 1223 belt then I do not have HD cooling, and the HD cooling belt is shorter than the EXC HD cooling belt:
122.375" for EXC HD cooling
121.5" for HD cooling
Perhaps there are some trucks that have smaller fan pullies (and shorter belts) which would cause the fan and water pump to turn faster for the same engine RPM.