thanks for the previous replies... trying to narrow down production year
does anyone know production year when Donzi moved the helm from port side to starboard? The one I'm looking at has port steering, closed cockpit walls (no storage compartments as in later years) and key-clue, a full width solid cast polished metal dash board for helm instruments, and passenger grab bar with signature DONZI name cast in the middle.

Assuming that you have found no HIN on the stbd side of the transom most likely a Donzi of this vintage would instead have a number under the deck in the general area of the gauges.
That is where most of them are found .
You'll need a flashlight and have to get on your back but they're normally written in heavy black pen and are under a layer of glass so they don't wear off over time .
Your number should begin with C18 . If you can find it it would be the answer to your questions .

thanks.. I've looked up under the dash and no numbers or lettering can be found.. my clue I think is with the solid cast metal dash overlay that has Donzi in the centre above the newer Livorsi speed and tach. The dash is full width with a passenger side grab bar I've scoured the Donzi registry pics and have not found a similar port hand dash. Furtherm the cockpit walls are sheer with no storage openings as I've found with 80's plus boats.

Don't get thrown off by the metal dash over lay or the grab rail with 'Donzi' stamped or engraved on it . These sound like they were pieces that were fabbed up by a previous owner to customize his boat a little . On the very earliest Donzis the only things that I know of that had 'Donzi' stamped on them were the original 'horned' lifting rings , and that probably predates your boat anyway .
I'm not really sure about the cockpit liner without the storage cutouts that you speak of . In fact this could be a red flag that it isn't a Donzi but a clone .
One of that vintage should have the handwritten pen hull number under the deck where I spoke of earlier .
Some pics would definitely help the experts out there narrow this down .