I have taken a ruler to every late model Japanese V6.  All are way too
tall. The Audi V6 is close, and would fit in a Syncro. I have looked at
most late model American V6's, but not all.
    I have been looking for engines to fit in a Vanagon for over 3 years.
I have been to a few junk yards that had a couple of THOUSAND late model
engines on the shelf.  I have yet to find one that fits very well.  Some of
the I-4's can be squeezed in, at least in a Syncro.
    The Toyota Previa I-4 engine lays on its side but has a huge water pump
sticking out which would stick out the back of the van.  Other than that it
would be perfect.

    John
    Vanaru.com