All you do is push the bottom portion of the seat towards the trunk the best way to do this is to kneel down if front of the seat. Then there will be two bolts holding the top portion along with the seat belts remove thes and then lift the top half from the bottom out of the support brackets.
Two lug nuts on the rear seat in the trunk
The battery is located under the rear seat.
Use an axe
On a 79/80 Deville there are nuts under the seat that have to be loosened and be careful of the power seat wires and mechanisms under the Seat.
Cadillac did not produce a DEVILLE convertible in 1983. ELDORAO yes. If it is a 1983 DEVILLE convertible, its custom made. To start remove the lower rear seat cushion and inside trim. Sorry I cant help further not knowing its customizing technique.
pull up on the front part of the seat
I believe its under the rear seat.
In the front right of the engine, and under the rear seat.
Behind the rear seat, access through trunk.
The battery is located under the rear seat (passenger side).
To remove the front seats from a 1997 Cadillac DeVille, start by disconnecting the negative battery cable to prevent any electrical issues. Then, slide the seat all the way forward to access the rear bolts, and remove them using a socket wrench. Next, slide the seat back to access the front bolts and remove those as well. Finally, carefully lift the seat out of the vehicle, disconnecting any electrical connectors for the seat controls if necessary.
It is located under the rear seat. The seat is easily removed by lifting sharply on the lower front lip of the seat.