[Billy-O]

Kind of hard for me to say what's amiss inside that tranny-rear. I wouldn't feel too good right now, but,.... It's your call to decide whether to investigate further. You could find a sheared key, stripped spline, busted teeth, etc... etc....

Any chance to drain the oil and check for metal in the drain pan?

Parts are likely hard to find and maybe might be better to find a used rear to interchange.