There are two versions of the model, on early ones the filler caps were 'cup oilers' from a bicycle wheel hub. These were found to be expensive and were eventually replaced with the red plastic items shown on the left below. My 'cup-oiler' version was missing the lids. I found a vintage car component website which can supply these but as it would cost me £10 I decided against it. I eventually found a very scruffy model on eBay at a very low price that still had its lids intact. After buying it I had an anxious few minutes getting them out - they are just a push fit, but I succeeded and put them in to the model below. Its probably better using contemporary ones as they are obviously old like the model, new ones would have looked too shiny and wrong. The later model with plastic caps tends to get a small premium.
