I managed to replace mine without lifting the body. I did jack the body a bit to create a bit of space as already mentioned.
The problem with the '100' is that a lot of the bits are fitted to the body or chassis before the two are joined. Changing AHC pipes is a right pain.
Before:
View attachment 156515
After:
View attachment 156516
I had to put a couple of 'Rivnuts' into a body cross-member to retain the pipe bracket.
View attachment 156517
The job is a bit of a pain when you're lying on your back under the truck.
Bob.