MOTORCRAFT

PART# / HEAT RANGE
AWSF-32C / stock heat range - copper plug
AWSF-22C / 1 Heat range colder - copper plug
AWSFA-12C / 2 Heat ranges cooler - copper plug
AGSF-32C/ Recommended for FRPP heads(not sure on heat range)

NGK

PART# / HEAT RANGE
TR-55/ 3951/ Stock Heat Range
TR-6/ 4177/ 1 Step Colder
BP7EFS (PN - 3526) BR7EF (PN - 3346) two steps
R5724-8 (PN - 7317) two and a half steps
R5724-9 (PN - 7891) three steps
R5724-10 (PN - 7993) four steps

AUTOLITE

PART# / HEAT RANGE
764s / Stock
103s / 1 heat range cooler
AR94 / 2 heat ranges cooler
AR93 / 3 heat ranges cooler
AR92 / 4 heat ranges cooler

CHAMPION

PART# / HEAT RANGE
YS-59C / -3 or -4 below stock heat range

DENSO IRIDIUM

PART# / HEAT RANGE
IT16 / stock heat
IT20 / -1 heat range
IT22 / -2 heat ranges
IT24 / -3 heat ranges