The doors of a Land Cruiser 40 are prone to rust, especially in the bottom. Fortunately, there are welding parts to buy. I bought door skins fromcoolcruisers.com and am very happy with the fit. This article is about restoration of ambulance back doors. There is also an article about the front doors. This is basically the same, so first read this as it has more details, see Door Skin repair.
I had bought a new floor from teseven-toyotaclassic.com. This had no recess for the door at the bottom, in the rear sill. This prevents the door from closing. But since I anyway had to weld in the lower part of the doors, I made the doors 8 mm shorter to avoid this problem. But it also means that the door weatherstrip at the bottom does not fit so this must be cut away at the bottom and replaced with a thinner V-strip.
See photos for details. Click on an image to get the image carousel.
See also Welding sheet metal and Sheet metal work.
Here are several Land Cruiser 40 topics: land-cruiser-40