Manual steering box 73-76 abody cars

I will get your shipping quotes to you, I'm verifying what gear box this is from, it was attached to the 73-76 suspension set-up (center link-disc brakes )
but was in a 68 a body car.
What is the difference between a 72 & earlier & 73 & newer manual steering gear?
I just want to make sure I'm selling correct information. Lawrence