I have designed a kit that converts the troublesome "torpedo fuses" used in the fuse box of early Porsche 944s and 924s to the reliable and widely available mini fuses. 

This kit is not a pure drop in, you must solder the board to the contacts in the orginal fuse box (this requires a powerful soldering iron and some skill). 

The kit comes with boards for the smaller and larger fuse boxes and fuses of appropriate rating for all positions along with 2 25A, 2 15A and 3 7.5A fuses as spairs.