good to know...
in that case there may be physical obstructions that are blocking the tie-rods or steering arms, etc., from reaching their limits (this was previously mentioned, or implied, in a previous post by another contributor).
as steering devices are usually employed that inherently have more travel than necessary available to them and need to be artificially limited to prevent tires from rubbing on fenders, etc.
you could even be having problems with the spindles and king pins...
but to verify if the box or if the installation is the problem, it might prove beneficial to disconnect tie rod ends (and i understand this is much easier said than done) and manipulate the box independently from the steering wheel alone. and if it still proves to only turn a limited amount (which would mean, of course, the the box or the steering wheel or column was the problem), i might even go to the extreme of then disconnecting the steering wheel and column from the box and manipulate the box independently from everything so as to rule out the steering column and wheel, etc.
this is simply a process of elimination.
and in the end, if the box is the problem, i guess you could take it back to whomever did the rebuild. and if the installation was the problem, it should be readily apparent as to what's hitting what down in there in the steering area.