Ok, so its not the original engine. Deck is probably 10 years older. Engine made 3/10/85 - so 35th birthday next week. Spooky 85 is 35 years ago
As you have given a nice clear photo, here is the exact IPL (part list), the manual is the correct one.
Plus here is another doc that might be handy - Actually, it won't come up as its too big. Will try to work out another way