You can buy a very nice made one from here:
http://terrawagen.com/products
I had installed one on my ex 91 Vanagon Hard Top and it
was fairly easy to install. There are some simple mods required
to your sliding track upon install but you will get good directions.
There is also the roll your own route of buying another arm and
cutting/welding it to your existing one. You need two to make one
longer one. Your welding skills or having access to a someone who
does is important as that part does get quite a bit of stress on it.
Trying to do it with a flux core mig won't cut it.

Bill M
87 Westy
Zetec Turbo

On Mar 3, 2013, at 1:22 PM, miguel pacheco <mundopacheco@GMAIL.COM> wrote:

> I'm trying to fit fatter tires on my Syncro and looking for that Sliding
> Door extension. Anyone know of a good source? Is there more than one choice
> and, if so, how do they differ?
> Muchas Gracias!
>
> Miguel