Catalytic converter. You need the front left.
I went to google, typed in "1997 ford explorer 5.0 left catalytic converter", hit the shopping tab and it took me right there.
Once on rockauto, look in the exhaust section and catalytic converter is highlighted.
MAGNAFLOW Part # 23312
Direct-Fit; Federal Emissions (Exc.CA); Not For Sale Or Use In The State Of California; Front Right
$160.99
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MAGNAFLOW Part # 23311
Direct-Fit; Federal Emissions (Exc.CA); Not For Sale Or Use In The State Of California; Front Left
$162.79
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WALKER Part # 53275 Ultra Direct Fit Converter (Rebate/Promotion Available!)
Front Right; Fed. & Calif. Emiss. Models.; Not legal for sale or use in the state of California.
$186.79
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CATCO Part # 4881 Direct Fit; Not Legal For Sale Or Use In The State Of California
Front Right; Federal & California Emission vehicles. (Only 3 Remaining)
$196.79
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BOSAL Part # 0794099 Direct Fit
Front Right ; Not Legal For Sale To The State of California
$198.99
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CATCO Part # 4882 Direct Fit; Not Legal For Sale Or Use In The State Of California
Front Left; Federal & California Emission vehicles. (Only 3 Remaining)
$200.79
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BOSAL Part # 0794100 Direct Fit
Front Left ; Not Legal For Sale To The State of California
$204.79
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WALKER Part # 54268 Ultra Direct Fit Converter (Rebate/Promotion Available!)
Front Left; Fed. & Calif. Emiss. Models.; Not legal for sale or use in the state of California.
$213.89
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EASTERN CATALYTIC CONVERTERS Part # 30363 21.25" Overall Length
DIRECT FIT; Rear; Not legal for sale or use in the state of California
$270.79
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BOSAL Part # 0794101 Direct Fit
Dual Converter Assembly; Rear ; Not Legal For Sale To The State of California
$284.79
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MAGNAFLOW Part # 23310
Direct-Fit; Federal Emissions (Exc.CA); Not For Sale Or Use In The State Of California; Rear
- Stocked in outlying warehouse--shipping delayed up to 1 business day
$285.79
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CATCO Part # 9029 Direct Fit; Not Legal For Sale Or Use In The State Of California
Complete Assembly, Rear; Federal & California Emission vehicles. (Only 1 Remaining)
$307.79
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MAGNAFLOW Part # 447102 Legal For Sale To The State Of California
Direct Fit CALIFORNIA OBDII CONVERTERS; Tier 1; Engine Family Number : VFM5.028GFEK; THIS PRODUCT IS IN COMPLIANCE W/CALIFORNIA REGULATIONS
- Stocked in outlying warehouse--shipping delayed up to 1 business day
$307.79
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MAGNAFLOW Part # 447101 Legal For Sale To The State Of California
Direct Fit CALIFORNIA OBDII CONVERTERS; Tier 1; Engine Family Number : VFM5.028GFEK; THIS PRODUCT IS IN COMPLIANCE W/CALIFORNIA REGULATIONS; Front Left