So the $3.9B question.

No shuttle extension, means there will be "the gap".

How much will it cost us to contract the Russians to send up
an Orion docking adapter for attachment to the shuttle
docking port?

Or is it a de-facto Orion requirement that it be able to
dock with the existing shuttle docking port?

What was the original Constellation CEV plan for this?
Use an Ares V that an Orion would rendevous and dock
with and then tranport to the ISS for installation?

Also AFAICT we have no US equiv to a Progress vehicle.
And no Ares V. So what's the plan?

Dave