Shortening an axle

[TJVigilante]

My housing is 56.5" from end to end, so that housing that's loose should work out fine with the shafts I have...i think it measured at around 60" at the bearing retainer plate?

Everything online points me to that diff being a posi, except for the fact that it's got spider gears and a center pin block instead of clutch disks...perhaps the original owners opened it up and replaced the posi stuff with open spiders? Makes no sense.