The Army combat enginers had something that sounds like what you are talking about. It was mounted on a Mercides Unimog chassie. The backhoe was a Case 530 and a front loader that was made by Case. You could operate the loader from the back hoe seat and could use the back hoe to move it around. It was imported, then built by Freightliner for the Army. It had a top speed of 65 mph. In low transfer, it would crawl a wall. You would need to take some sea sickness pills if you were going to drive at highway speeds. It worked fairly well if you were well versed with it's operation, but it could be a pain in the butt if you dident have a clue.
They were being phased out when I retired from the Army in 1998 and a few National Guard units still had them untill 2005. It was called a CEE and thats all I can remember about them model wise. I looked through some old Army pictures and couldent find any, but i am sure that it can be found some were on the internet