There is a TS4 engine in the Commercial Vehicle Museum at Leyland. At first it looks just like a TS3 until you look a little closer at it. Did a bit of work on them in the '60’s but when I worked at the Derbyshire quarries in the '70’s they were very popular with the 4 wheeler owner drivers (excellent on fuel, 19+ mpg) until the Clydesdale’s came along to replace them when they were life expired!
Pete.