Takes a special puller to pull off the needle and re-install at zero. Maybe a clock repair shop? BTW found a great video on rebuilding speedo, was for a 55 Pontiac but the guts inside were just about same as my '46 pickup. Best of luck

It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed