[dsraven]

you can see in post 8 the pics shows the envoy floor inside the 57 gmc cab.it is too narrow as you see by the envoy kick panels on each side. the nice thing is you get a trans hump, a console shifter=cable operated and set up for 4l60E,a console if desired,a firewall with mounted brake booster and a single pedal for automatic vehicles, and a mount for a gas pedal for drive by wire.there is a nice round grommetted hole for wiring to pass through on the firewall and a steering column hole as well,however it may be low. use the steering column as well if possible.if you use the floor as well you could also use the seats which come with integrated shoulder belts. measure up what you need and keep in mind that the envoy has the trans hump offset to the pass side a bit. don't just cut the same amount off each side and expect it to be centered.