I had an old phone company van with a three speed, floor shifter.
The shifter broke off, so I cut a hole in the floor, and attached two 1x2's to the transmission.
Push in the clutch, pull up 1x2 #1 and go. Push in clutch, push #1 down, and pull up 1x2#2, and go,.... Etc. worked great!
No one else could drive it. So I got a free anti-theft device too!
I was lucky, only had to mess with first and second, the car was a four speed, third and fourth still used the gearshift.