Back in 1964, gas station magnate Leon Hess decided his chain of Hess stops could contribute some seasonal cheer by offering one-of-a-kind toy trucks. The durable, battery-equipped Hess trucks soon became prized by kids and adults alike; Hess releases a new truck every year, and the annual releases have become something of a collector’s item.

If you think a model might be lurking somewhere in your attic, take a look at eight of the most valuable Hess vehicles on the market according to dealer Ray Patterson of RaysHessToyTrucks.com. But remember: Values are typically based on the truck being not only in excellent condition but with a pristine package. Collectors don’t offer as much for a model that’s missing its box or parts.

1. Hess Tanker Truck (1964) // $1800

Courtesy of Ray's Hess Toy Trucks

The first-ever Hess truck issued is not only rare, but it came with a feature not commonly found on subsequent trucks—the ability for a child to fill up its reservoir with water and then spray it out a nozzle. The headlights also light up. Hess made roughly 150,000 of the 12-inch trucks, and one that’s mint in the box is valued at $1800 or more. The original 1964 price? Just $1.39.

2. Hess 'Red Velvet' Truck (1967) // $2550

Courtesy of Ray's Hess Toy Trucks

This fuel truck is sought-after for its unique accessory: a red velvet display stand. The pedestal was part of the packing material and was easily damaged, making one in mint condition hard to find. Models can reach $2500 on the aftermarket.

3. Hess ‘Woodbridge’ Tanker Truck (1969) // $1500

Courtesy of Ray's Hess Toy Trucks

You’ll need to look at the box to find out why this model is so desirable. The packaging states “Home Office in Woodbridge, New Jersey,” which didn’t typically appear on the boxes. You can expect to pay $1500 if you find one.

4. Hess Fire Truck (1970) // $525

Courtesy of Ray's Hess Toy Trucks

After several years of green and white trucks, Hess decided to change things up in 1970 by issuing their first fire truck. The design was modeled after actual trucks used at Hess refineries and had a detachable ladder. You can expect to pay around $525 for this model, though 1971’s version of the fire truck is a more lucrative find. After Hess ran out of boxes, they shipped that model in a plain box and had retailers put a “Season’s Greetings” sticker on it. Intact, the whole package can sell for $3500.

5. Hess Barrel Truck (1975) // $3500

Courtesy of Ray's Hess Toy Trucks

This box truck features fuel barrels and a sliding door. While most of 1975’s models were made in Hong Kong, a handful were manufactured in the USA and had some slight differences, including a lack of “Hess” on the tires and a “Made in USA" marking on the box. With only 20 to 40 made, this model can sell for $3500 or more. The regular version sells for around $375.

6. Hess Tanker Truck with Black Switch (1977) // $375

Courtesy of Ray's Hess Toy Trucks

Hess issued similar tanker trucks in 1977 and 1978, but the 1977 version has one important distinction—some models have a black switch on the body instead of a red switch. Thanks to this variant, it can sell for $375. (It would be 1980 before Hess issued another truck. They skipped 1979 due to a nationwide gas shortage.)

7. Hess Training Van (1980) // $375

Courtesy of Ray's Hess Toy Trucks

Not a truck but a van modeled after the company’s training vehicles, this anomaly was also notable for being the first Hess product to come in a one-piece packing box. It can sell for $375.

8. Hess Truck and Airplane (2002) // $75

Courtesy of Ray's Hess Toy Trucks

Not too many modern-era Hess trucks sell for considerable sums because collectors treat the products and packaging with reverence. But this recent-vintage airplane and truck combo is worth $75 or so. The truck has a flatbed that can haul the aircraft.