I am trying to get my brake lights to work and it looks like i am missing the fuse. Why is there 3 sets of prongs to hold the fuse?

 

Actually the brake lamp fuse is above the one you're missing. The one with the three prongs is the instrument lights and takes a short 9A. The prong next to it is another fuse thats missing the prong that goes in the empty slot.

 

It could be the angle of the camera or the lighting but the stop light fuse element appears to be broken. A quick continuity check with a test light can confirm this.

 

Yet another reason to get a factory Chassis Service Manual. As Eric correctly points out, the 20A fuse above the missing one, which is labeled DOME STOP, is the one that powers the brake lights. The missing 9A fuse powers the dashboard instrument circuit (thus the INSTR label). The third clip in that row is one half of the feed for the Jetaway kickdown/converter circuit (TRANS). The other clip and associated wire wasn't installed on MT cars.

Also note that the 64s used a combination of AGC, SFE, and AGA fuses. AGC fuses are all the same length. SFE (society of fuse engineers) uses different length fuses based on amperage - higher amp fuses are longer so you can't install a 25A fuse in a 9A circuit, for example. AGA are similar to SFE.

 

Glad to see a diagram posted. I find it peculiar that "bay" contains two fuses without a vertical post separating the two fuses. Hey, what do I know. Except I wouldn't design a fuse panel to support two fuses in the same bay without separating those two fuses.

 

Well, fortunately the two center (back-to-back) clips are the common hot ones, so not a lot of danger there. Plus, as an engineer and designer, that sure looks like a last minute "OSIF" change (oh $#!t, I forgot...)