Lighting, Light Fixtures, Ceiling and Exhaust Fans - Fixture Mounting

I currently have an old exterior wall-mounted fixture. I would like to replace this fixture, but am having trouble finding one that has the same mounting holes. The currentl fixture's escutcheon has it's mounting hole spacing closer than any fixture I've come across. I'm guessing I must have some type of non-standard plastic wall box as the holes are only about 2-1/2" apart.

I'm looking for suggestions on how to get around this problem without replacing the whole wall box.

Thanks.

Your house sounds like it was built in the 50's. The junction box you have is smaller than those we use today. With the newer boxes and a spanner bar, you can install either the 2 1/2" or the larger fixtures in the same box. But in your instance, you will probably have to change the box out to accomodate today's span. I have seen where the newer spanner is attached to the smaller box, and allowed to extend over the edges and the new fixture attached to it, but you may have to drill drop back holes in order for your screws to sink properly.

look for a fixture with the spider web back brace. circle with slots and holes at varying distances. 99% of the time this has fit every hole config i have come across.