I'm thunking that they meant possibly pre-'47. I seem to recall (and I might be wrong) that the earlier 216s used a smaler diameter pushrod, 3/8" dia instaed of 7/16" (again, I may be wrong. Jerry, help me out here! ).
As to the rods working, I think they will. But new repalacemnt rods are relatively inexpensive, about $8 apeice for a 235/261.
