Aluminum 3946074 heads
 

I have a set of these heads with "Motion" stamped on them. Is it possible they are Baldwin Motion heads? If so, what other signs should I look for, and will that increase the value? I noticed these heads on eBay go between 4 and 5K.

Can you provide some photos for us to look at?

The value of the heads will be in their condition and the dates. 1969 and early 1970 dates make them more valuable.
I have never heard of "Motion" being stamped on aluminum heads on Motion cars but I am certainly not an expert.