I have seen it on the majority of vanagons.  I have yet to see anyone re-install it on replacement of the cross over pipe.

Sent from my iPad

On Mar 12, 2013, at 16:57, mark drillock <mdrillock@COX.NET> wrote:

> The screw and hook was likely there when the van was new AFAIK. I have
> seen many vans with it, all years.
> 
> Mark
> 
> 
> John Meeks wrote:
>> On Tue, Mar 12, 2013 at 2:51 PM, neil n <musomuso@gmail.com> wrote:
>> 
>>> Hi Stuart.
>>> 
>>> Thanks. Yes I'm familiar with the cross over tube. I didn't see a
>>> fastener holding cross over to van on the tank I R&R'd on my '81 and
>>> tank I pulled from an '85.  I was asking and attempting to clarify.
>>> 
>>> On Mon, Mar 11, 2013 at 11:49 AM, Zoran Mladen <zmaninco@yahoo.com> wrote:
>>>> ....  Keep in mind that the crossover pipe is secured to the body in the
>>> middle with a single screw and hook.
>> Yeah I thought that screw and hook reference was a bit odd. Nothing like
>> that on the '84 OR '91 I've replaced tanks on.
>> 
>>