Lock out box
The 550 spyder was equipped with a four speed manual gear box. To reduce the risk of accidentally gearing into reverse, the engineers designed a lock out gate which stopped the gear stick from going into reverse unless the hinged, spring loaded bracket was opened. The configuration was with the reverse gear in the top left position, which had to be depressed to change it from the forward gears to the reverse gear. My spyder is similar, but with the reverse in the bottom right position. I have had fabricated a similar box to serve this purpose and to look period correct plus more importantly functional.