I was thinking about getting an aftermarket digital speedo in addition to the stock digital unit. The didgital one still work fine, but it has that anoying 85 mph cutout where it just flashes afterward (if you have one, you kow what Im talking about). Im just wondering if anone has ever tried this, and if so, will the stock speedo sender unit work? I would just use the afermarket one above 85, so I dont want to get it if the stock one cannot still be used. I love my digital dash, espacially since it has never been attacked by the electrial gremlins that I keep hearing about that seem so common on these cars. Another question I hae is there is a wierd box type thing (electrical) under the passenger seat with a 7 pin computer style harness on it. It looks like a factory job to me, ut I could never figure out what it was for. Its never been hooked up as long as I have owned the car, but Id stll like to know what it is. Thanks for ay help,

 

Ya',.......... I tried this - And was glad I did. Now I can get Speed readings over 85 as well as 0-60, top speed and quarter mile times. I can also adjust the speedo if I change the rear gears and the size of my tires. ( & I've changed gears and tires several times since installing the aftermarket speedo !! )

Here's what it looked like while the 700R4 was installed and it was mounted on the dash ( I used the original speedo sending unit and tapped into the VSS buffer) :




Here's what it looks like now that the T56 is installed & I modified the original cluster to hold the aftermarket one:




Also - I've owned 25-30 third gen camaro's and I have never seen anything installed under the passenger seat like you describe. Sounds like something left over from a previous custom installation..... a cd changer maybe, or an alarm, or an old cell phone harness perhaps !!