Assuming the headers(heat exchangers) are out of the way, it' pretty straight foreward.
Channel locks for crushing the old tubes.....this is the brutal part...crush & twist.....oh, drain the oil first:lol:
Clean up the new/old tubes including the internal O rings. Coat liberialy with silicone *grease*. same, same with the other O rings. Clean out the bores....more grease.
Shove in one side...as I recall, do the head side first..the small end in there...there's just enuff room to get your fingers stuck.... then the other....it's not that easy, but it can be done. Expand the tubes enuff to expose the circlip slot. Snap that puppy in place. One down, 3 to go. Don't bother putting bandaids on you knuckles till they're all done

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