I have that old transducer type on my 78, replaced the transducer a couple of years ago and it works great, The only feature I miss that newer cars have is "RESUME" and the "ACCELERATE". I miss resume the most though.
This system will decelerate though, you just hold the button till you get to the lower speed you want and release.
Sorry the pics so big, but here's the instructions that came with my truck when it was new for the old transducer type cruise control. this tag came ffrom the dealer hanging on the turn signal stalk. This was a dealer installed item.
