Steering gear box/coupler

[sjarrett71]

I replaced my old leaking power steering gear box in my 71 4x4 last week (before the ice) and the coupler was too small for my new box. I got it on with a large hammer but the bolt wouldn't go back in because it spread apart. I researched the part number before I bought the new box and it was the same for several years so I assume it is the right box. The PO put the p/s on as the truck didn't originally have it and I remember from other threads that there were 2 sizes of shafts/couplers on the boxes. Is it possible that the p/s the PO put on was from a newer truck? Does anyone know what size shaft I have, it should be the bigger one I'm assuming. Does anyone know where I can get a new or good used coupler that actually fits? isn't it neat to find all the stuff that a PO did that was not correct when you go to fix something?