Depends on if it's an early car or not - I think mid '67 (by '68 for a fact) they went to collapsible steering colums and the pitman arms were bigger - I tried to swap the '67 arm to my new '68 box (for the collapsible steering column) and it was too small. If you have a solid steering column, its the small one - if it has a rag-joint and collapsible column, its the big one, I can almost guarantee you.
I have later production 67 with the short steering shaft and rag joint, but I don't know if the colum is collapsible or not. Were all of the short shaft steering rods with the rag joint connection to the steering box collapseible?
Whatever the case, it sound like I'll need the 1 1/16" pitman arm puller. Thanks for the info.