I beleive the 83 has only three wires going to the rea speakers, One is common for both. Most any modern steroe head unit or amp requires 2 separate wires for each speaker, no common connection at all. So you should plan to add a wire or just repalce the set. 

 

The wires head up to the roof are near the glove box. Remove the box and you will see where they head into the pillar. Rarley will this be an easy pull to get a new set of four larger wires to the rear. It can be done. Other wise run a new set underneath and go up into the cabinet. Due to the lenght I would start with at least 14 gauge. If you plan on power amps and stuff consider 12 gauge. 

 

Dennis

 

> Date: Sun, 16 Jun 2013 22:19:24 -0700
> From: moyald@GMAIL.COM
> Subject: rear speaker wires, '83 Westy
> To: vanagon@GERRY.VANAGON.COM
> 
> My '83 Westy has a short in one of the rear speaker wires. I want to
> replace both. Can anyone describe the routing for these wires, so I can
> minimize interior disassembly? Thx much, David