Same boom was used for all Day Sailer models, the block locations/configurations changed, but basic boom was same. You could check the Forum on hte Day Sailer Association web page,
www.daysailer.org
You do not need to be a member of the Association to read and or post on the forum, but there is a no-charge registration to post.
Javelin did use same boom, that is correct. If it helps, here are the specs: