Early 833 ID???

Love all the spinning wheels.
Easy answer since its a ball and trunion, It WILL be a 64-5, the casting numbers wont be needed. the raised pads dont come in till 68. Plus the gear ratio is 'marked' on the imput shaft in front of the splines, and I can see it is a 3.09 gear trans.
Now switch all the gears into a 66 up trans and use a slip yoke and get 3.9 gears on a 3.55 rear end.