This may be one of the first Chang Jiang queries on here.
I did some digging and there is a serious lack of info on the CJ. This was about the best I found but doesn't really answer your question.
https://b-cozz.com/chang-jiang/
If you can, head over to the 'Everything Else' forum towards the bottom of the Technical/Performance Section and start a thread there with some pics. We like pics.
I have read that the year of manufacture may be located in the frame number but I wouldn't bet the farm on it.