The power steering box is physically longer by an inch or so, so the length of the power box steering shaft is shorter than the manual box shaft. The factory shaft, power or manual, is meant to telescope in and collapse upon impact and is held together with plastic injected into drilled thru holes, forming a 'pin', that breaks upon impact. Some guys just break the pin and shorten/lengthen the shaft as needed. Also the manual box input shaft where it joins the coupler is physically larger than the power steering box input shaft, requiring a different coupler. The couplers are interchangable, but it's a bear to get the plate that holds it together properly crimped to hold it in place.
