This is from the Craftsman Warranty webpage that was linked to.
TOOL STORAGE
21. Tool Storage, Homeowner's Level CRAFTSMAN LIMITED WARRANTY
FOR ONE YEAR from the date of purchase, this product is warranted against any defects in material or workmanship. With proof of purchase, a defective part will be replaced free of charge. This warranty does not apply to a product that is damaged or altered through transportation, misuse, abuse, corrosion, accident, neglect modification or mishandling, nor does coverage apply if the product is ever attached to a moving vehicle.
This warranty is void if this product is ever used while providing commercial services or if rented to another person.
WARRANTY SERVICE
With proof of sale, call the following number to obtain free replacement of defective parts: 1-888-331-4569
22. Tool Storage, Standard Duty Level CRAFTSMAN LIMITED WARRANTY
FOR THREE YEARS from the date of purchase, this product is warranted against any defects in material or workmanship. With proof of purchase, a defective part will be replaced free of charge.
This warranty does not apply to a product that is damaged or altered through transportation, misuse, abuse, corrosion, accident, neglect modification or mishandling, nor does coverage apply if the product is ever attached to a moving vehicle.
This ONE YEAR warranty is void if this product is ever used while providing commercial services or if rented to another person. For 90 DAY commercial and rental use terms, see the Craftsman warranty web page.
WARRANTY SERVICE
With proof of sale, call the following number to obtain free replacement of defective parts: 1-888-331-4569
23. Tool Storage, Heavy Duty Level CRAFTSMAN LIMITED WARRANTY
FOR SIX YEARS from the date of purchase, this product is warranted against any defects in material or workmanship. With proof of purchase, a defective part will be replaced free of charge. If a replacement part is unavailable, the product will be replaced with one of equal value. This warranty does not apply to a product that is damaged or altered through transportation, misuse, abuse, corrosion, accident, neglect modification or mishandling, nor does coverage apply if the product is ever attached to a moving vehicle.
WARRANTY SERVICE
With proof of sale, call the following number to obtain free replacement of defective parts: 1-888-331-4569
24. Tool Storage, Premium Heavy Duty Level CRAFTSMAN LIMITED WARRANTY
FOR AS LONG AS IT IS USED from the date of purchase, this product is warranted against any defects in material or workmanship. With proof of purchase, a defective part will be replaced free of charge. If a replacement part is unavailable, the product will be replaced with one of equal value. This warranty does not apply to a product that is damaged or altered through transportation, misuse, abuse, corrosion, accident, neglect modification or mishandling, nor does coverage apply if the product is ever attached to a moving vehicle.
WARRANTY SERVICE
With proof of sale, call the following number to obtain free replacement of defective parts: 1-888-331-4569
25. Craftsman Evolv Tool Storage CRAFTSMAN LIMITED WARRANTY
FOR ONE YEAR from the date of purchase, this product is warranted against any defects in material or workmanship. With proof of purchase, a defective part will be replaced free of charge. This warranty does not apply to a product that is damaged or altered through transportation, misuse, abuse, corrosion, accident, neglect modification or mishandling, nor does coverage apply if the product is ever attached to a moving vehicle.
This warranty is void if this product is ever used while providing commercial services or if rented to another person.
WARRANTY SERVICE
With proof of sale, call the following number to obtain free replacement of defective parts: 1-888-331-4569
26. Craftsman Truck Boxes
Note: Duration of coverage varies according to Duty level as specified below. Check product package or instructions for precise length of coverage.
Standard Duty: 3 Years
Heavy Duty: 4 Years
Premium Heavy Duty: 5 Years
CRAFTSMAN LIMITED WARRANTY
FOR THREE YEARS (or other duration) from the date of sale, this product is warranted against defects in material or workmanship.
WITH PROOF OF SALE, a defective part will be replaced free of charge. If a replacement part is unavailable, the product will be replaced with one of equal value.
This warranty does not apply to a product that is damaged or altered through transportation, misuse, abuse, corrosion, accident, neglect, modification or mishandling.
WARRANTY SERVICE
With proof of sale, call the following number to obtain free replacement of defective parts: 1-800-832-7494
If your box is twenty years old I doubt it's the "Industrial" line. If by some chance it is.
Tool Storage
Note: To determine the correct warranty coverage time period for your tool storage item, you will need to know the product series (Standard Duty, Heavy Duty, Premium Heavy Duty, 3000, 5000, 7000 or 9000). First find the item number on the identification tag in the chest or cabinet top drawer. Then find the product series in the Craftsman Industrial Catalog on the same page that lists the item number. CRAFTSMAN LIMITED WARRANTY
During the warranty time period specified below, this product is warranted against defects in material or workmanship. With proof of purchase, a defective part will be replaced free of charge. If a replacement part is unavailable, the product will be replaced with one of equal value. This warranty does not apply to a product that is damaged or altered through transportation, misuse, abuse, corrosion, accident, neglect modification or mishandling, nor does coverage apply if the product is ever attached to a moving vehicle.
For each product series, the time periods of warranty coverage are as follows:
Craftsman Standard Duty: 90 Days
Craftsman Heavy Duty: 6 Years
Craftsman Premium Heavy Duty: Lifetime (for as long as product is used from the date of purchase) Craftsman Industrial 3000 Series: 10 Years
Craftsman Industrial 5000 Series: 10 Years
Craftsman Industrial 7000 Series: Lifetime (for as long as product is used from the date of purchase)
Craftsman Industrial 9000 Series: Lifetime (for as long as product is used from the date of purchase)
WARRANTY SERVICE
To obtain warranty coverage, contact the distributor from which the product was purchased.
Proof of purchase is also mentioned a number of times.