Cruise control - we all love it until it doesn't work and then it's one of the more complicated automotive systems to diagnose and repair. When planning your Subaru motor conversion you have a few options when it come to having a working cruise control system on your Vanagon.
If your van has factory cruise control it's easy to integrate it into your conversion with a simple part from an early model Subaru 2.2 Legacy from 90-94. The vacuum actuator from this era was all mechanical and it is easy to modify to use in your conversion even with later motors. Run a hose from the stock Vanagon cruise control pump to the Legacy actuator (as shown in the picture below). Mount the Subaru actuator somewhere convenient on the fire wall and hook up the cable to the throttle body in the slot right next to the van's accelerator cable.
You might need to find some pliable silicone hose or something similar as the nipple on the Vanagon pump and the nipple on the Subaru actuator are slightly different sizes. If the cruise does not work after this mod, ensure that the hose is tight on the fittings.
For those of you without factory cruise equipped vans, you have another set of challenges, none of which are insurmountable. There are several auxiliary stand-alone cruise control systems on the market. Most come with comprehensive instructions and are not difficult to install as long as you take your time and wire them in as directed. The kicker is that ALL require splicing into your existing wiring and mounting a proprietary control unit somewhere near the driver's controls.