does anyone know of a steam shunter n gauge that hasz gauge running gear as i wish to make a narrow gauge track on my n layout
Try searching for "Nm" or "Nn3" gauge models, these are to N scale but running on Z gauge track representing metre-gauge.
There are body kits that use Marklin Z chassis, eg Peco NG652
http://www.gaugemaster.com/item_details.asp?code=PENG-652 (http://www.gaugemaster.com/item_details.asp?code=PENG-652)
(http://www.gaugemaster.com/_upload/imgs/lrg/34363/PENG-652.jpg)
There are some expensive hand-made brass models