anderson awning window operator

I'm afraid I don't really know what part numbers you're talking about. These are often not reliable when choosing replacement hardware, even for a brand name like Andersen. Going by the appearance and dimensions of the old components is always best. Now, you ordered the 39-390. This has arms of 11" in length. There's a long arm version of this operator, the 39-389, which has 15" long arms. Let me know if either of these is what you needed.