It took me several hours of driving wishing I had a cruise control and thinking about where to put the switch. On this car ash trays were not obvious when they were not pulled out so it wasn't until I was designing some sort of hinged pull out flap sort of thing in my head that I started kinda feeling around the dash to see what I had to attach to. Felt something and first thought was dang it something is in the way right where I want to mount it. It all makes sense because a well designed ashtray would be within easy reach of the driver which is also where you want the cruise switch(s).
All you really need to make it work is to tie onto your existing brake switch, a set switch, and some sort of speed sensor. I think the best option especially for GM who almost always seemed to use the same speedo cable connector is the inline cable one. I think they also sell a magnet thing you stick to a driveshaft but that never seemed like the cleanest and most reliable idea to me. That is how the Sears ones from the 70's I remember seeing worked. I think there were some that just used a tach signal from the coil but I don't think they were very smooth since they were monitoring the engine speed, not the road speed.
They have a couple options for the cable ones and it comes with a coupler that threads into the transmission then you thread the cable into the sensor. If you are dealing with a car that had cruise you can install the sensor where the old sensor was assuming you have room to route the cables. OE sensors tended to have the cables coming out the same end. These are inline so cable routing needs to be different since you can't have sharp bends in the cables.
