Good subject, Keith!
Here's the situation on my truck. There are two 6-in-a-row junction blocks, the metal pieces are "oval" rather than "square" shaped, so they are most likely replacements. This could well be the result of work done by previous owners in the UK (the wring is a bit of a mess, really).
Here's an example of how this junction block was replaced by a fuse block - not a bad idea in itself, by the way....
H.