Mine is an 85 Tintop.  Bought as second owner in early 1989.  No modifications to battery box behind passenger seat, all intact including battery hold down clamp.
I added a "house" battery about 10 years ago to box under Driver seat.  I used the GoWesty kit, and they included a bracket to hold down battery.  So if any of you folks are looking for a hold down bracket, give them a call and I bet they can help you out. 

 http://www.gowesty.com/product/auxiliary-battery/3567/auxiliary-battery-kit-1980-83-air-cooled-and-1980-91-non-campers-?v=
By the way, since my electrical requirements are low, I use the WalMart Group 41 batteries.  On both sides of van.  Works just fine.  Don't need all the deep cycle stuff and related charging apparatus.  I have a modest inverter (150 Watts I think) which is ample for the laptop and charging camera and cellphone battery.

      From: Stuart MacMillan <stuartmacm@GMAIL.COM>
 To: vanagon@GERRY.VANAGON.COM 
 Sent: Friday, May 11, 2018 8:57 AM
 Subject: Friday survey for Westy owners
   
Okay folks, I'm curious about something. How many of you camper/Weekender owners have unmolested battery boxes behind the passenger seat? How many intact boxes have you seen? I’m not going to bother to ask how many still have the battery hold down clamp.

The box on my ’84 was fine because I bought it when it was only two years old, and I’m not an idiot. But, both my son’s ’87 and my current ’85 have butchered boxes. Mine is sawed 3” down both sides for easy bending (hard on the carpet), and my son’s box back edge was hammered into oblivion. 

It’s too bad Westfalia Werks didn’t put an instruction label on the battery cover, it was a terrible oversight. 😉

Stuart