Mike:
Maybe there is more difference between the oil pans than we think.  I
performed the same test you did this past summer and recorded different
results.  I posted these results to the list in November, 2000 :

http://gerry.vanagon.com/cgi-bin/wa.exe?A2=ind0011D&L=vanagon&P=R16837

I just tested again (the oil pan is still off!).  At 2.75 qts the water
begins to run over the rear left lip of the oil pan.  Maybe the 5 speed oil
pan is deeper (does the elimination of the flat steel crossbar permit
this?).

Maynard     OvO '79
'82 Westy Diesel "Reinhardt"

<southard@GIS.NET> wrote:
<snip>
> I'm pretty sure that the
> static oil level in the pan is above the gasketed joint between the oil
pan
> and block on the left side of the engine.
<snip>

<mwsnow@HOME.COM> wrote:
>
> Don't bet on it.  We measured with the oil pan off the engine when I was
> having oil pump pickup problems.  It was a bit unscientific, but 4 quarts
of
> water fit in the pan when the bottom of the pan was on a level surface.
> Certainly, the oil sloshes, splashes, and drains all over the gasket on
the
> lower side of the engine.

mwsnow@home.com wrote:
<snip>
> The engine carrier bars are curved differently and mount to the body
using a
> different bracket system.  The rubber motor mounts are moved to the new
> location and redesigned to eliminate the flat steel crossbar that goes
from
> side to side on the 1982 vans.
<snip>
>
> The oil pan itself is interchangeable with the 1982 model, but
incorporates
> an updated drain plug design and a threaded hole on the side of the pan
for
> the turbocharger oil return line on TD vans.