In 1999(or there about) Airstream went with
a Bargman light on the Classic.
It is referred to as 6''x4'' but is 5-1/2to5/8'' x 4-1/4''
which is the lens measurment.
Bargman came ups with a LED Retrofit that allows
you to take out two screws, pop off the lens, and
insert the LED light. It is a Very easy install!
For the Back-up light, Bargman has two offerings.
The first one looks like original with a red frame.
The other one is solid white/clear. (Below)
We also have the screws for these lights if you have
lost yours or they are real rusty.
LEDs For Recreational Vehicles