as far as i am aware that is what it is for
makes up the length so the coloumn reaches the shorter manual box
converts from power steering spline on your coupler to new manual box spline.
I have not tried it, so no real world experience other than having two boxes to compare
but i do know you have both length and spline issues to overcome ad this appears to do it
MRE - Manual Steering Adapter
looks like the old Mopar performance one.
unless you car has full chassis strengthening, a cage tied into the front rails etc id be inclined to use this kind of adapter because it allows you to maintain the slip/flex coupling on the steering column steering shaft.
protects the upper race in the steering box from movement of the front chassis rails and bulkhead.
Solid UJ coupling does not, which is fine if nothing flexes and moves. in a standard car they do flex and move at each corner and bump in the road.
Dave