I had a 4" lift on my 75 K5, & I needed no d-shaft mods. I just ran conversion joints. We have a really good parts store here. I just went in & took the 2 joints I had & told them what I needed. The parts guy walked to the back & got it w/out looking it up.
No conversion joint is needed for the front, If the 60 has the stock yoke on it still.