In the half of 1995 the freon changed to R-134, so the 1994 models will have R-12. You can get a kit to change the system over to R-134 for around $45.00. The R12 is hard to find and is very expensive. If your system has R-12 in it, you will need to see a air conditioner specialist to remove it due to the ozone properties.
That would be the 4L80E transmission.
For a brand new 2013 Chevy Silverado SS, the price ranges from $23,500 to $45,000 depending on what kind options you want on the new 2013 Chevy Silverado.