My '95 has the top cover. I have had it off because I was trying to twist the whole knob to get the print lined up, and somehow figured out the top cover would move. I twisted that knob all I could by hand, and was about to bust out a pipe wrench when I found the cover would move.
Having said all that, I don't know if there is bolt under it... didn't even look once I got the print oriented correctly.
'95 SMB E350 Quigley 7.3
... If you have to ask, you'll never understand...
"... torpedo'd, because we don't generally cotton to bullshit around here." -jage
"... do they ooch apart in the night?" -Dia