#318 & tender swaps

I model the Ouray branch of the D&RGW and own an Overland C-18 #318. It has an incorrect tender that appears to be more like #271's. The correct tender is supposed to be a flair sided tender with coal boards.Does the Colorado Railroad Museum have the correct tender for #318.In the latter years the #318 used #340's tender.When I was there this past summer there were several tenders on the grounds.The tender with the model appears to be #315.What engine did this tender belong to #315 ?. What tenders numbers are located at the Colorado Railroad Museum. Were tender swaps usually done during repairs to engines or tender rebuilds and was this typicaly a short period of time.