Hello Zach, That old caulk is “Dolphinite”. Now just named “Dolphin” Bedding compound. A good product. You can get by not using bedding compound on the end of the sprit but positively use something to seal the 4 screw holes in the side, whether you use those screws or not. (They’re not really necessary). Unfortunately Dolphin costs about $50 a quart and you would only need about a tablespoon. Good luck with the project. Dave