Possible transmission or differential issue

62TE 6spd transmission. At a light went to accelerate and wham, felt like hitting a curb. Able to drive to side of road. Suspect transmission blew up, it is a sealed only "service tech" check type. Been really dragging my feet on this one so plenty of time to think. Seems the motor mounts are both broken. Car starts but tons of noise and will not shift into any gear or that's what it seems like. Pulled axles and started the process of removing the transmission. A person who is listening to my description (council of motorheads at work) thinks it is possible that it is the differential that is what is broken and not the transmission. The differential gear pack hangs off the back, so I have to remove the tranny to service it anyhow. Do you think it is plausible it could be the ring gear or the differential gears in the carrier? Where do I get a replacement? Is this a problem: the differential blowing up separately and not the transmission?