steering coupler/rag joint confusion

[greasy68]

I have read up on some of the older posts but I am still a little confused. I bought a power steering gear box to replace the ps gearbox I had on my 68 longbed 2wd. The splined coupler has a flat spot and so does the input shaft of the new gear box but the input shaft is too big for the coupler/rag joint. I went to autozone and they walked me over to the univeral rag joint repair kits. No luck. Advance auto parts just said no and did not look it up in the computer or book. Just "no". It sounds like there is multiple steering couplers from what I have read. I am going home during lunch to count the splines and get an accurate measurment of the old and new input shaft on the gear box. Does anyone know for sure how many different sizes there are of input shaft on the gear boxes? How many types of couplers there are? Any help would be great.