Try this. Go to https://www.lionelsupport.com/. Search by Product, enter 6-14588 into the text box and click the Search button.
This will bring up several possible options. You will need to decide which is appropriate to your engines.
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Clicking on >View Parts will show you multiple pages of parts for the selected model. Once there, each part will usually have a description, clickable photo of the part, price, and option to buy directly from the website.
I hope this is helpful.