I wonder if it was a dealer modification. Maybe it originally came with the volvo but Jim-Bob came in there and said "that sure is an awesome boat! Too bad it's got the Volvo drive and not a Mercruiser. If you swap it out, i'll buy it!" Looks like they added the teak to give the extra space for the Mercruiser manifolds. Just seems like if Glastron did it, they would have changed the fiberglass cover a little to make it work.
Either way, it's cool! I love the apricot color too.