I am looking for the service manual for my 75 ELPTO, ser # OT183191. The part number for the manual is 830234R04. I have found pdf version of 830234R03 which looks like an older version for engines up to 1997, of the same manual. I have not been able to find any pdf manuals online for 830234R4. Is worth my spending the $80 for Revision 4? I'm thinking that most of the procedures are very similar.