You can do all this with the seat still in the car, although it takes a bit of agility to work under the seat frame.

Armrests and seat frame were strengthened by gilt wood edging too and continued from the armrests up to the back of the chair.

Bench seat stanchions were moved inboard to reduce bending stress in the seat frames, allowing them to be lighter.

For the first few years of production even the seat frames were made of aluminum.