I went to the Costco selection site and it seems to say that batteries installed in a diesel are warranted for less.
"If a passenger car battery is used in a diesel vehicle (not including passenger automobiles), truck more than one ton, lawn tractor, snowmobile, or recreational, service or marine vehicle, etc., the limited warranty is reduced to a free-replacement period of six months or half the standard length of that battery."
"If a passenger car battery is used in a diesel vehicle (not including passenger automobiles), truck more than one ton, lawn tractor, snowmobile, or recreational, service or marine vehicle, etc., the limited warranty is reduced to a free-replacement period of six months or half the standard length of that battery."