Transmission

I just bought this jeep and it has a 360 motor in it and it has a 4 speed and the best I can tell from reading, it looks like it is going to be a T18 transmission. Is this the transmission that would have came in a 1978. Also, would a 360 have came in this or would it have been a 304. The reason that I am asking this is because when I was changing the oil in the transmission, there was several chunks of metal that came out when I was changing the fluid. I have not drove it but from where I bought it to my shop. The guy I bought it from did not know anything about it but he drove it on a regular basis. He did say it would jump out of third gear some time. Would all of this be factory or has everything been changed out

Transmission