No power to fuse box

Your first job should be to determine what caused the problem. You really need a shop manual. There's a 73 you can download free, but there ARE some differences in the wiring

Go to MyMopar

http://www.mymopar.com/index.php?pid=31

Some of the manuals there, as well as that one, came from here, by the way. I've got a 74 paper only manual, it will take me awhile to sort this out

Also at MyMopar are some aftermarket SIMPLIFIED diagrams which are not quite correct, and not quite complete. They do have one advantage .....they are sometimes easier to follow

http://www.mymopar.com/downloads/1974/74DartA.jpg

http://www.mymopar.com/downloads/1974/74DartB.jpg

So far as replacing the box, there are several ways to go. A member just asked that last night

Here:

http://www.forabodiesonly.com/mopar/showthread.php?t=331988