Rear springs

[TheGovernment]

I have a 86 T and it's an inch lower than the GN's of that year from factory. I need new back springs but am unsure if oem GM ones will raise the car up to much in the back, or why the 86 was an inch lower to begin with. I work at GM and can get OEM springs for pretty much nothing. I'm not looking to lower it anymore than it is. Does anyone know the part number of the ones I'd need. There are 6 different ones on the computer at work and I have no idea which ones they would be.

thanks