VW Vanagon bodies, 1980-91, air-cooled, water-cooled, 2WD and 4WD are all 95% identical. The bodies of '86-91 2WD and 4WD are 99% the same. Most of the differences between the 2WD and 4WD are in the various systems (suspension, cooling, fuel, electrical) and are bolt-on. There is actually surprisingly little welding to do. So, it is feasible to convert any 2WD Vanagon to 4WD Syncro EXACTLY the way the factory did.
The cost to take a rust-free, crash-free 2WD Vanagon and convert it to 4WD Syncro is between $25,000 and $50,000. It all depends on the condition of the vehicle, which determines how many of the systems have to be completely rebuilt (as opposed to simply converted). It also depends largely on the gearing and engine displacement chosen, as well as what type of differentials are used: open, limited slip, or fully locking. Here are a couple of articles to read on this topic:
"Decoupler and Solid Shaft vs. Viscous Coupler
So, the decision whether or not to start with a particular Vanagon is entirely dependent on its condition, and whether or not there is any emotional attachment.
In order for GoWesty to advise one way or the other with regard to whether it makes sense based on condition, the vehicle would have to be inspected. The first step we always take when any vehicle comes to GoWesty for the first time for any major work is to assess the entire vehicle and give our opinion as to whether or not it is a good candidate for a conversion. That is our policy and is, of course, in the best interests of all concerned. With regard to emotional attachment... well, that is an entirely different story. We have resurrected Vanagons from the dead for people who knew full well that it would be cheaper to simply replace their beloved vehicle. In matters of the heart, I am no expert.
Here are the basic steps to convert a 2WD Vanagon to a 4WD Syncro:
1. Replace transaxle with Syncro type
2. Move engine and transaxle assembly down 2" to accommodate fuel tank and drive shaft
3. Eliminate 2WD fuel tank up front, install Syncro fuel tank above transaxle in rear--add fuel filler door to rear (and delete front one)
4. Remove 2WD front suspension and cut out steering rack mounting and lower suspension mountings
5. Install Syncro front sub-frame, suspension, and front differential (the rear suspension is the same as 2WD), and drive shaft
6. Change over parts of the cooling system and add Syncro-only wiring harness
Six simple steps, right? Not quite. It takes one very talented GoWesty technician—with access to every tool imaginable—about 60 hours to strip a 2WD undercarriage clean, convert to 4WD, and install all fresh and rebuilt everything. As of April 2010, we have completed 12 such conversions.
There are three reasons to convert a 2WD Vanagon to 4WD (rather than simply buying a 4WD model):
1. 2WDs are typically in better condition. That is, 4WD vehicles generally see rougher conditions and more severe weather, so they tend to be rustier and more hammered overall.
2. To create a Syncro model that is rare (pop-top models) or did not otherwise exist at all (for example, a 1990/91 Multivan Weekender that was never offered in 4WD).
3. If you're starting with a mechanically worn-out 2WD, a full restoration typically takes about 200 hours. The mechanical portion of that restoration usually takes about 40 hours... so what's another 20?
If you want a hard-top Syncro, it is probably less expensive to simply find a 4WD model. That is, the hard-top Syncros are much more common and affordable. In fact, in order to convert any 2WD to 4WD, you need a hard-top donor anyway. So, one way or another, you will have to buy one.
But if you want a pop-top Syncro, it can actually be less expensive to buy a nice, rust-free 2WD pop-top and a hammered, worn out Syncro hard top as a "donor" for your conversion.
Any way you slice it, though, a fully restored Syncro—pop-top or hard-top—isn't going to be cheap. The newest Vanagon sold in the USA rolled off the assembly line in 1991. These are old vehicles, and even the nicest and newest and lowest mileage examples are in need of extensive restoration and modernization. Plus, they are RARE beasts. Add this all up, and it just might make sense to create a Syncro Westy rather than trying to find the perfect one...