I thought I heard a while back that Elon said an upgrade would be made available to upgrade the older 60s to a 75. This is interesting to me because I have found a super good deal on a 60 - almost no miles on it, and loaded otherwise. But, in the long term, I need the extra range. Has anyone heard if this upgrade has been made available, and if so, how much? And I wonder why, if they can upgrade it to a 75, why can't they upgrade to a 90 or 100? I guess possibly size limitations.