I don't have a speedo cable in my 94, so I cant tell you. I think my picture should help with the screw I'm talking about.
The rachet head does not fit over it 100%... but certaily enough to get it off.
Once removed, the 2 relays will move enough to help with removal. Should have more than enough room to get the butter knives in.
Again, I've never taken out the entire relay.
As you said, your model year is a bit different, but with the right tool, you should be able to get that screw out.