A conversion van just might be the ultimate party-mobile. I can't think of any vehicle I'd rather have at, say, a tailgate party than the Mark III conversion van I recently tested. It's the equivalent of a mansion on wheels. About the only thing missing is the Jacuzzi. Mark III, located in Ocala, is the nation's largest van conversion business. The company churns out luxo-vans and fancy pickup trucks for automakers. Although a Mark III conversion adds a hefty chunk of money to the window sticker, you get a lot for the dollar. A conversion van is probably not a great vehicle for everyday transportation. Instead, out-of-town weekend jaunts, football-game parties and family gatherings are where a vehicle like this really shines. Locally, you can check out Mark III conversion vans at World Chevrolet/Geo in Orlando. Other brands of conversion vans are available at other Central Florida Chevy dealers. PERFORMANCE, HANDLING Chevrolet serves up the Express van with a variety of engines. Base models come with a 4.3-liter V-6. Three V-8s and a diesel engine also are on the menu. Regardless of the engine, only one transmission is available - a four-speed automatic. Ourtest van, sporting a 220-horse power 5.0-liter V-8, performed admirably, despite being weighed down by a multitude of items that comes as part of the conversion package. Acceleration is smooth and quiet but not especially quick at low speeds. I found the van is best on the highway at cruising speeds. It's a great vehicle for long trips. At 55 mph or 65 mph, the Express is a breeze to drive down the highway. It is not bothered by crosswinds, and the long (135-inch) wheelbase provides an even and stable ride. The suspension system consists of standard-issue items for big rear-wheel-drive vans. There is a live axle bolted to leaf springs looking after things in the rear; up front, an independent coil spring suspension irons out the bumps. With a 45.1-foot turning radius, the Express requires a bit of finesse when parallel parking and maneuvering into tight parking spaces. However, the power-assisted steering makes it easy to turn the wheel. The Express is outfitted with power front disc/rear drum anti-lock brakes. During hard stops the front end dives a bit, but the brakes grab quickly. The anti-lock system works quietly; there is not much pulsing or feedback felt in the pedal. FIT AND FINISH The dash is about the only thing that isn't changed during the conversion. The rest of the interior, from the door panels to the headliner, is ripped out and replaced with more luxurious trim from Mark III. That trim includes enormous amounts of timber (on the doors, roof panels and window sills) as well as thick leather upholstery on the seats. There is also deep, rich carpet and color-keyed floor mats. Mark III installs electrical gizmos galore. Our test van sported a color TV and a V CR (with remote control), rear air conditioning/heating system, jacks for video games and a cellular phone, and an electrically operated rear sofa. A button on the overhead console allowed the driver or passenger to raise or lower the sofa. When folded down, the sofa is large enough for two adults to take a nap. When folded up, three adults can sit on it. Because the center row of seats consists of two captains chairs, there is plenty of room for seat passengers to move around while the van is in motion. Our test van came equipped with power windows, mirrors and door locks; cruise control; AM/FM/CD player; a full gauge package, and alloy wheels. The Mark III conversion is a high-quality job. The specially designed door panels and wood trim not only fit well, they also were designed well. The interior looked very professional. Nice touches abound, such as the built-in cup holder in the side door, running boards, two big bay windows and the built-in, removable flas hlight behind the driver's seat. My gripes are few. With the rear sofa in the up position, rear visibility is restricted, because the headrests block the rear windows. I never felt at ease while backing up, partially because the van is so large and partially because I didn't feel as if I could see well behind the van. Also, the interior lights worked intermittently. I could never tell if they would come on or not when the driver's door was opened. Still, a conversion van is a nice way to travel, especially if you don't want to spend the big bucks on a mobile home. Specifications: Base price: $22,929. Safety: Dual air bags, anti-lock brakes. Price as tested: $28,215. Incentives: None. EPA rating: 14 mpg city/18 highway. Truett's tip: The full-size Chevy Express conversion van is comfortable, well- equipped and pleasing to drive. It just may be the next best thing to a motor home.