I devised a cunning yet simple way to slow those speedy 6v wipers after a 
12v conversion. It works a treat on my '65.

I used some full-wave bridge rectifiers. They contain 2 useable diodes in 
each unit, and each diode drops the voltage .6 of a volt, so thats 1.2 v for 
each bridge. 5 of these units means a drop of 6V!

Each bridge has 4 "spade" connectors on it, labelled +, -, and two with 
squiggles. Daisy-chain the 5 bridges together by connecting the + to the - 
on each subsequent bridge (leave the all the "squiggle"  terminals 
unconnected). So at the ends of the daisy-chain you should have one + and 
one - terminal left over. Power from the fuse-box goes to the - terminal, 
and the + terminal needs to be connected to your wiper switch. Magic, 6V 
wipers! Use this for your guages, clock  etc too.

The bridges I bought were from a local electronic shop. I got some 35 amp 
ones cos I couldn't get anything smaller (type KPBC3504), so they were 
overkill and more expensive than needed (it ended up costing me around $35). 
They also came in a square die-cast pakage with a hole in the centre so they 
were easy to mount onto some steel with some self-tappers.

Ask your electronics store for anything over 10 amps and you should be OK 
(they will also be about half the price). Try to get the ones with the spade 
terminals just to make life easy, and mount them on some steel or a proper 
heatsink so they dont smoke - especally if you're going for 10 amp ones.

Cheers big ears,
Steve J.
'65 Bus, wifes daily driver
'69 Type 3, my daily driver
'60 T1 Ghia , previous driver tried driving it on its roof - its now broken 
but fixable.