Open? .... Posi?

I had this center section sitting for about 15 years i pulled it out to use it and i think it is a open rearend...? it is a 489 case with 411 gears ... who would put 411 gears in a open rearend?
The other picture is the 741 case out of the car it has 3.23 gears in it.
Can the posi unit be swicthed from 741 case to 489?
Also is that rearend Open?

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