The way that I understand it (and I've only used a Case with an eagle-hitch once)... There's no modification necessary. MOST of your CategoryI 3-point-hitch implements will hook right up to an Eagle-hitch.
your not referring to the motor lift system are you? the end the arms will have a round hole in them. These were designed to lift cultivators. To correctly use eagle hitch it's best to have 3rd link that bolts over pto shaft. Sometimes hard to find.
i remember using eaglehitch three point. the problem is the arms dont sway, meaning it's difficult to steer with impulment in ground.i'm a machinist, if someone could email some specs i could machine out the top link that fits over pto my email is [email protected]