Only 40amp? The bolt-in fuse on my parents '90 626 was an 80amp, easilly purchasable at Canadian Tire, not sure about in the US, but it should be easy to find, it's a standard fuse.
There was an extra, unused space in my sister's prelude engine bay fuse fox, so for her amp, I got one of those bolt-in fuses and used that for a super-clean install. They have them in many ratings, hers I used a lower one of course. It's been many, many years, but it was probably a 20 or a 30amp bolt in fuse.
This is the one you're looking for, right?
![Image](http://ecx.images-amazon.com/images/I/41o0shvD4rL._SL500_AA300_.jpg)