It most certainly does matter. Like Rusty said, transmissions built before 71 do not have the part throttle kickdown valve in the valve body and do not kickdown.
Don't unless you want to take the parking pawl out and possibly brake the case.
Thanks, I learned something. Ignorant question: So, do the pre-71 "kickdown" linkages vary the pressure to cause the upshift to be at a higher rpm, but cannot cause a shift down to a lower gear?