I was driving the teener to Target on Saturday

Once I get to Target I take a look at the fuse box... FUSE 9 is blown. I figure, no biggie, I haven't changed these fuses in years. So I load a new '8' into FUSE 9. Drive around some more and it shorts out again in about 10-15 miles.
Anyways, just wondering if there are any 'obvious' issues with a blown FUSE 9 on a '75 that anyone has seen before I start testing everything....
Also, anyone have a list of whats on FUSE 9? My Clymers guide wasn't too descriptive....
THX for any help!