I recently inquired about using these. Just wanted to report back that these will work just fine in a Marvin Tilt-Pack replacement window situation, where the track is vinyl. These should be installed on the upper sash, not the outer frame.
Attaching photos of this installed. I think it would be helpful to add something like this to the product page. If not my photos, how about the ones from Andersen's product page?
One of the other customer questions is showing a different product, which I found a bit confusing when trying to evaluate this product for my use. I think it might be helpful to others if you can clarify that the "Vent lock doesn't reach the sash" is really about the other product.