That's exactly where I started. The DNR could verify that the registration numbers were for an alumacraft boat, but that's about it. The last time it was registered was long enough ago that they have no record of a hull ID so they wanted to verify it. I've had a few conversations with them (all very cordial) and they said once I've exhausted all efforts to locate a hull ID on the boat, they can generate a new one and I'll need to affix it to the hull in a tamper proof way. I'm going to have some plates made and will rivet them in. Here is the guideline in my state (WI):
State and Federal regulations require you to permanently affix this number in two places. The primary hull identification number in watercraft with transoms shall be affixed to the starboard outboard side within 2 inches of the top of transom, gunwale, or hull deck joint, whichever is lowest. The duplicate hull identification number shall be affixed in an unexposed location on the interior of the vessel or beneath a fitting or item of hardware.
-Each hull identification number must be carved, burned, stamped, embossed, molded, bonded, or otherwise permanently affixed to the watercraft so that alteration, removal, or replacement would be obvious.
-Use of a plate must be fastened so that removal would cause scarring or damage to surrounding hull area.
-Hull identification number characters must be no less than 1/4 inch in height and not attached to any removable part.