There are many different slide mechanisms used in the construction of vehicle mounted drawer systems.  Whether you are buying a product or building your own, here are some of the options to consider.  

Heavy Duty Full Extension Drawer Slides

These are the cream of the crop, such as the Accuride 9300 series slides.  They are production style ball bearing steel slides expertly designed and crafted.  They offer an incredibly smooth action and are full extension, which is very convenient for loading and unloading your drawer.  They contain very robust mechanisms and are rated for as much as a 500 pound load.  Be aware, though, that this rating is based on an 18” long slide in an 18” wide drawer, and not for vehicle based applications.  For mobile applications they are rated for a 300 pound load on an 18” slide in a 32” wide drawer.  However, most drawer systems will require a slide much longer than 18”, so the rated load will be somewhat less.  This should not deter you, but you should understand that a 36” slide is not rated for the full 300 pounds once you mount it in your vehicle.  These heavy slides are available with a lock-in, lock-out, or both feature- very handy when parked on a hill.  These slides require little to no maintenance and should last a lifetime if not abused.  The tradeoff is that they are the heaviest and most expensive slide mechanism on the market.

Medium Duty Full Extension Drawer Slides

These medium duty slides are similar to their heavy duty brethren, but are less expensive.  They usually do not have locking mechanisms and come with a much lower load capacity.  In general they may be a good choice for small drawers or slide out trays, but are not robust enough for heavy drawers or fridge slide applications.

Ball/Roller Bearings

Some drawer systems use skateboard wheel-type ball bearings and a runner (usually square steel tubing) as the sliding mechanism.  They are a much more cost effective option than drawer slides, and are usually lighter overall.  However, they can be difficult (but not impossible) to keep from rattling and do not allow full extension of the drawer.  They have no integral locking mechanism, so a separate mechanism is needed.  As long as these limitations are acceptable, a bearing and rail system is a good inexpensive option.

Solid Runners

The simplest and least expensive solution is to use simple low friction runners or strips mounted to the bottom and/or sides of the drawer.  This is also the lightest and most space efficient solution.  A very thin strip of UHMW (Ultra High Molecular Weight) plastic, for example, can be attached to the bottom and sides of a drawer and cabinet to create a relatively smooth action.  However, care should be taken to prevent the drawer from opening too far and creating a dangerous condition.  Alternatively, a travel limiter can be fashioned to keep the drawer from opening too far.  This is a good solution for the most hardcore rock crawler types, where weight is a greater concern than the average overlanding rig.