Thoughts Needed on Oil Slinger for 400

I'm replacing my harmonic balancer on my '82 F-250 with a 400 -- the balancer had started to separate.
I decided to go ahead and replace the front main seal because it seemed to have a small leak.  Once I got the old seal out, I could see the crankshaft sprocket and timing chain.  I think I'm missing the oil slinger.

The shop manual shows an oil slinger between the sprocket and timing cover.  Could this be part of my leak issue?  Should I be concerned?  Is this something I can replace without opening the timing cover?

The Illustration portion of the master parts catalog also shows an oil slinger - basic # 6310.  But the parts list for the 351M & 400 doesn't show one, as you can see from the snippet below where things are listed numerically.

My guess is that both the shop manual and the illustrations are generic, meaning they were prepared for any 351M or 400, but that by the 80's that part had been eliminated.  So I don't think your engine had one.  

And you cannot put one in w/o removing the timing cover.  So if you have checked the timing chain for slack and it is fine I'd do w/o the slinger.  But you don't want to get that close to the timing chain and not check it.