On the high pressure line, there are two sizes of the square teflon o-rings, depending on which end of the hose, available from your local Ford dealer.
388897-S (smaller diameter) rack end
388898-S (larger diameter, slightly thinner) pump end
Can be tricky to install...suggest soak in hot water to soften, then carefully install on fittings and wait for them to return to original size before installing line/fitting back into car).
Rubber o-rings from the dealer (bag only so you pay for several) for the EVO:
384975*S94 (pkg of 10)
391032*S (pkg of 4)
387571*S100 (pkg of 10_
Additional rubber o-rings are in a power steering rebuild kit from a parts house.