The deal is, there isn't one.

I have a pretty nice vanaogn here that belongs to to intellegent educated
people and only one of the 6 rear running lights was working ..
all the rest, long, long ago corrodded or burnt out.

And the car had recent work to the tune of too many dollars for not that
much ..
but no one ( ? ? ) ever checks the tail and rear running lights ?

There is a technician named 'No Body' ..
that's who checks things like brake lights , tail light, side markers, back
up lights , license lights ...
No Body ..that's his job, and who takes care of it usually .......No Body.

and the Tail Light Fairly is a myth...
though not everyone realizes that yet.

and since there is no Tail Light Farily anymore...modern cars have warning
systems for that..
just like my 88 volvo does ..and Volvo  had that warning system years before
that.

the bottom line ..
like Tire Pressure ...SOMEBODY'S got to check it .
( well,   now there's a gov enforced electronic Tire Pressure Monitoring
system on all new cars ......
so I guess the gov gave up on the Tire Pressure Fairly too. )

be safe.
Check rear lights ...might keep you from getting stopped by the poh-lease or
being run into.
The bulb and wire contacts  corrode like so many things on 25 year old
vanagons can.

be safe !
scott