This website provides a service manual part# cross reference and you can buy from them.
Ken Cook Co. sells Original Product Literature Supporting 1996 and Older Outboard Marine Corporation Products, limited supply of original printings of Johnson, Evinrude, Gale, and OMC manuals are still available. On older literature, we may provide a machine copy reproduced from a master file...
www.outboardbooks.com
This is the only BRP/Evinrude authorized entity to re-print 1996 and older OMC manuals and sell them to the public if this company does not have them in stock.
They provide the OEM factory manual that was from Johnson/Evinrude, not the SELOC or Clymer garbage.
503150 I believe is the part number you are looking for. Please verify this is correct yourself before purchasing that service manual.
You can also use that part# to look up on E-Bay for people listing the factory service manual for sale. I think I seen 3 to 5 for sale at the time of this posting.
FYI, always come prepared first to give model number and serial number before asking for help or parts in general. You won't get far without it. (Evinrude/Johnson, Mercury/Mercruiser, Yamaha, Suzuki, etc.)