Hi,
I went to Memphis Equipment and found that they have 3 M135/211, or more specifically shells of such trucks. The red truck there has a floor that wouild be considered okay, but certainly not stellar. I told Mark that someone may call. The concern was getting the floor out. You may wish to purchase the hole cab instead and turn it over. It seems to be a couple of sections and Isuspect the quality of metal may be better by replacing the metal with something new instead of putting in another complete floor of less than perfect quality.
I will say this, the folks @ Memphis Equipment were very kind and patient in answering questions. Glenn & Mark a very knowledgeable pair of guys and made us feel quite at home so close to closing time.