I'm 6'2" and have been routinely banging the top of my head for a few years. But last week I hit my forehead!! Game changer. So I measured how high the liftgate was opening....68 1/2".
Lift support pair was $29.34 on Amazon Prime for the same Monroe's MacT used. An easy DIY job anyway, but made even easier by MacT's video (thanks MacT!).
BTW, if your'e doing this by yourself, my liftgate surprised me and dropped as soon as I pooped off the top of the first support. Wow, these things are shot! And the liftgate is pretty heavy. And puting the support on with one hand while trying to hold it up is not really an option. So I suggest you grab something long handled (I used a the telescoping pole I wash windows with and adjusted it to the perfect length to prop it open - but just about anything 6' long will do). A breeze to change by yourself after that
So new lift supports installed in less than 5 min. Now opens to 72 1/2". Now I'm back to like new - factory settings - just hitting the top of my head