came up my own version of a tube type shifter out of scrap i had lying about the garage.
used a section of 80's mustang column to provide the outer and inner parts
used the double d section as well as it matching outer section

on the inner section i welded a small section of square bar. this will be the reverse lock out

i cut a corresponding slot in the outer tube for the square bar to slide in to

welded on an end plate that mounts a spring loaded lever

the lever stops the shifter pulling into reverse

slotted the end to fit a ball joint. welded it to the column bracket on the top of the axle case

using tube to connect shifter to bracket on the box with ball joints at either end

the cockpit end will have a shift knob fitted

still not completely finished but it seems to work OK. does require both hands to select reverse but i can live with that