CRocker - that's a great pic showing the pre 94 and post 93 vs's side by side.
I snagged a copy of it. There are 2 differences but either JBox will work in any C10. Just last week I tested an '88 out in my '2000.
1. Horn Vs. Ignition label on the upper right fuse
2. Tail fuze label and fuse is 15A on the newer version instead of 10A on the older.