The Saurer RR-7 was built as an artillery tractor for the Austrian army. After Germany occupied Austria, the design was adapted as Sd.Kfz 254 and used as an armoured artillery observation vehicle for the panzer dvisions. It was used both on the Eastern Front and with the Afrika Korps.
A novel feature was the chassis which had wheels and tracks and could be converted between either mode. This allowed to combine high road speeds and good cross-country performance.
has more information about the original.
has some pictures of painted models (scroll down the page)