Posi or not?

[Mike Marentette <mmarentette@domain.elided>]

Hi all,

I've got a 74 Travelall 100 with the towing package.  It has a Dana 60
rear axle with the 5 on 5.5 bolt pattern.  I've been wondering if it has
or had posi at one time.  So I recently jacked the rear up to see if
both rear tires would spin the same way.  They did not.  I would spin
one tire and the other would stay stationary.  I'm puzzled.  My friend
says it's an open differential.  My experience with open differentials
is that if you spin one tire forward, the other would spin backwards,
not stay stationary.  I guess what I'm wondering is if it could be a
posi with the clutches burned up and no longer operational?  I could
pull the cover off and see for sure, but I want to see what input some
of you could give me before doing so.  I haven't checked the line
setting ticket because I would still be clueless.  Any comments are
greatly appreciated.

Mike Marentette