I have a 79. Can I remove the clear plastic cover and remove the speedometer to get to the cable? I think I found the cable and it runs into a little device. There is another cable that runs to the transmission. Is this the cruise control? Do I replace the top cable only or do I need to replace both of them?

On another note, the where the stock exhaust goes from one pipe to two in the rear, is there a factory mounting bracket there or is it from the guy who put my exhaust on?

 

The 'box' you are refering to is for the cruise control. What happens is when this starts to ware out, it puts tension on the lower cable until it eventually fails. I also heard that GM doesn't make replacements anymore, and that aftermarket ones are junk.

With my car, also a '79, I installed one single cable bypassing the cruise control which didn't work anyway. It's easy to change, and should only take about 15 or 20 minutes to replace, and you don't have to take the dash or speedo apart.

Put the car on ramps, or jack it up and put on jack stands. Reach under the dash until you find the cable, and follow it to the speedo. There is a metal tab you push to release it. Go under the hood, and pull out the cable, and a rubber grommit will come with it . Put the grommit on the new cable an fish it back into the hole. Push it on the back of the speedo and it will snap on. Put the grommit back on the fire wall. Craw under the car, and unscrew the old cable, and screw on the new cable.

I'm not sure about the exhaust bracket. Mine has duals with flowmasters, and no cats...