Can anybody he and the lp me with a F1 steering box question

[348tripower]

I am changing out a steering box in a 1950 F1. The replacemet box is a bit larger and the spline for thestering arm is 1.180 dia verses 1.040 on the old box. Anybody know what could be going on here?
Thanks,
Don

[enjenjo]

Most likely it's an F3 box and not an F1.

[348tripower]

Most likely it's an F3 box and not an F1.

Would the steering arms be the same length?

[enjenjo]

I think they are,  but heavier.

[phat rat]

ratio is different also

[348tripower]

Thanks guys.