Ah, that one. This is not a Logic specific thing, it is used by many applications. You should have got it via software update. And it used to be on the Apple website but it seems to got removed from there (did they have a reason? ...)
You may try the one from the link below at your own risk. So far I've read, some people could not install it on their system, others had problems with it. It may only be good for certain OSX and Logic sub-versions.
Thanks for quick answer however, I had tried that and it wont allow install to any of the drives. It seems it needs to be 4.0 even though they said "or newer"
I fot close as well with Pro Applications Update 2008-05 but the last one I found in my receipts on my old system was 2008-03
Hmm, I'm not sure about this one either. Could you provide some system details? Also, (I realise that this may not be the answer you are looking for) do you have Logic Pro 9, which IMO was in just about every way better than Logic 8, but with pretty much the same workflow (unlike Logic Pro X).
I'll have a dig around and see if I have any Pro App Kits archived, but TBH I haven't gone near L8 since 2009.
Edit: just tried opening 8.0.2 on my Mac Pro running OS 10.7.5.