83 mk1 golf gti fuse box

Hi, I have an 83 mk1 golf gti my fuse box on the car is very temperamental I've found the part code being 171941821d. I was at a boot fair recently and found a similar fuse box 171941813d for £2. Are they interchangeable as they look similar but I've found the fuel relay doesn't seem to go in the same position. Please help thanks in advance