Big big problem

I have 2000 chevy impala trying 2 install new driver side cv joint . went to pop cv axle out of transmission whole output shaft from inside tranny came out. IS THIS a simple replacement or is there a clip or something broken inside tranny?CAN someone help me with this asap please ?:uhoh:

The output shaft spans all the way through the trans (shafts, drums, and hubs) from the differential side (output) gear on the RH side of the trans. Not only would it be almost impossible to reinstall the shaft and align it with the output bevel gear, but the circlip locking the shaft to the gear would need to be installed onto the shaft once it is installed.

At the very least you will need to remove the RH differential extension housing, remove the pinion shaft and spider gears, and install the output gear and clip onto the output shaft. Then there is the question of where the pieces of the broken clip may have gone. If they are floating in a clutch hub in the trans it isn't a good situation. You would be lucky if they are still in the differential housing.