Cargo lamp - smaller bulb?

[davepl]

I'm making a 'hidden' third brake light inside my cargo lamp housing using a super-bright LED module. It takes up some room, however, and I don't have space for a full 1157 bulb. So, two questions:

1) What bulb is normally used for the cargo lamp? It looks like 1157 because it;s two pin, but its only single brightness and the pins are aligned. So what's a single-filament bulb that has two pins?

2) Given the answer to (1), is there a small-globe version of it?

Worst case I found this small-globe 23/8W replacement: BM-25-8047

Still, I sort of need to know what's supposed to be there before I can find a replacement!