What's the difference between a Ford F1 and F3 Steering box

I'm looking at buying a steering box out of a 1948 Ford F3 1 ton truck and wanted to know if there is any difference between the F1 / F3 box? Is it larger than the F1 or the same? It's going in a 1929 RPU
Thanks for the help

 

I think the pitman arm is larger center hole.

 

I don't believe there's a difference. I think that it wasn't until the F-5 that the box became bigger. If it is it's not that much bigger. Just get the pitman arm with it and you'll be ok.

 

The Ford parts book lists the same pitman arm, shaft/worm assembly and housing assembly for '48-'52 F1, F2, F3, so without going through all the individual parts it looks like they are the same.

 

I have a Big Ford truck box and turning it from lock to lock is like 6 turns opposed to my F1 box wich is about 3 turns. You can change the length of your pitman arm to correct it, just don't remeber if it's lengthen or shorten. Good Luck.

 

I checked out the box today and it's the same as an F1. I paid $80 for the complete column, wheel, steering box and F1 shock mounts......gotta love a good deal
Thanks again for all the information