That ute sound like the one my father owned for about 6 years.
It was a 1999 LX470 and it was converted on the Gold Coast.
It was cut behind the rear doors, a back panel with a rear windscreen was fitted, the chassis was cut and had 700mm inserted. A metal 2200x2000 metal tray was then fitted on the back.
Obviously, there was the usual tail shaft, fuel lines and electrical work as well as an engineer’s certificate required.
It also had an LPG conversion. It used to backfire from time to time and one day it blew the side of the motor out. You could put a tennis ball in the hole! Needless to say, 1 new (second hand) motor sans LPG.
This vehicle was only recently traded at Phil Gilbert Toyota Homebush for a new SR5.
Off Lexus onto Toyota, I own a 2002 GXL 100 series turbo diesel and I did the same conversion as previously described in 2006, and I do not think I will ever get rid of it.
It, as was the LX470, is a real head turner, great to drive but a bugger to park!