Q: Has anyone ever looked into the possibility of converting a Eurovan into a 4WD?
A: Yes, people have certainly looked into this idea. Read on, GoWesty Faithful.
Syncro (4WD) Eurovans were never offered in the U.S., although they were available in Europe and many other parts of the world. These were all manual transmission, full-time 4WD vehicles like the one pictured above.
Thus, it is true that parts are available, albeit used and in need of rebuilding—not to mention an expensive boat ride away. Since these vehicles were manual shift, the best candidates for conversion in the U.S. are the '93-'96 models with the 5-cylinder , which was available with a manual shift transaxle. These models could be converted at a fairly reasonable cost, and they would be totally legal in all states. All said and done, you could probably expect to pay around $25K for the conversion.
Converting a later-model Eurovan, '97-'03, is a totally different story. All '97-'03 Eurovans sold in the U.S. have a VR6 engine and automatic transmission, making the conversion much more complex—and, technically, illegal in some states. The issue with legality stems from these three intricately connected things: 1) the change from automatic to manual transmission that would be required, along with the shifter and clutch systems and main electrical harness, 2) the elimination of the transaxle electronic control unit (ECU) and harness, and 3) the needed change to the engine management ECU and harness. In many states, #2 and #3 are not legal.
You asked. We answered.