When you install a Detroit Locker into a Corp. 14 10.5" full floater do you have to re setup the ring and pinon?

Not if you pay attention to how many turns you make to the adjuster rings and put them back exactly where they were.
The most you will have to do if you somehow manage to botch the job is to reset the back lash.

from everything i gather when you install a detroit locker in a 14 bolt F.F. rear the detroit locker goes into the original case. does the case have to actually come out of the housing to do this or is it like the 12 bolt where you can get to the center of the carrier without removing it?

Yes the carrier assy has to come out.
Scribe a line on the adjuster rings and back each one off about 3 turns and the carrier will come out. Of course you have to remove the axle shafts to do this.
Remove the bolts that hold the carrier together and remove the spider gears and install the Detroit, bolt the carrier back together and reinstall the carrier in the housing.
Turn the rings back 3 turns to the scribe lines and lock them down.
Glue the cover back on, reinstall the shafts and fill the diff with 90wt.
Put the rig in gear and drive away.
That's about it in a nutshell.

Thanks for the info powermad. This is my first attempt at the 14 bff diff. I should have it in my hot little hands by friday. Then it's all about building it more bullet proof than they already are. :)

look at this:

http://www.off-road.com/chevy/tech/detroit/