Here is a link to a discussion about the Keystone letter and Lippert's decision to not warrant the Andersen (which it did previously). The Andersen and Reese Goose Box were the only non traditional 5th wheel hitches "authorized" for use on a Keystone trailer until Lippert "unauthorized" the Andersen meaning there were no non traditional 5th wheel hitches authorized on a Lippert frame other than the Reese Goose Box. Note that the Goose Box is now owned by Lippert giving them a financial incentive to remove the competition.
https://www.keystoneforums.com/forum...ad.php?t=46341
Call Keystone 1st and possibly Lippert if the answer is vague. If they provide a definitive answer please post back for the education of the forum.
Edit: Corrected the word not (auto correct?) to now when describing Lippert's ownership of the Reese Goose Box.