CJZ, I'm a 1997 Sunbird Neptune owner. And, I've often thought I would like to have an OEM manual for the boat. But, they just aren't anywhere to be had. Sunbird went out of business sometime between '98 & 2000. However, the parent company of Sunbird, "OMC", is still in business under the "Bombardier" flag. OEM manuals, parts, etc. can be found through BRP-Evinrude's web site @ Evinrude. iBoats is also a good place to get parts, too. Parts, info and expertise are not hard to find on Evinrude and Johnson products. Google is your friend!
Best of luck with your boat. Mine serves me well!