Dependant drop down list

One one sheet, I have a list of products, e.g.
Product 1
Product 2
Product 3

Products 1 and 2 can use Part A, Part B, Part C, or Part D.
Product 3 can only use Part XY.

On another sheet I have one column with a drop down to select the Product.
In another column, I want to select the Part used. So for Product 1 and 2 I want a drop down to only display Part A, Part B, Part C, Part D.
If I select Product 3, I only want to be able to select Part XY (or have the cell auto-populate with Part XY).

Cheers for any help.

Thanks, I'll give it a go.
The only problem is, is that I have a list of hundreds of products, most of which can use one of ten different parts, and a few that can only use the XY part.
Listing each product ten times for the ten parts could be cumbersome.

Thanks for your help.
In the end, I went a different way by using a helper column and dependant drop down lists.