Rear spool or locker?

Another question for the list.  Do they make a spool or locker for a midget
rear-end?  While removing the wheels from my parts car I noticed that I
could not turn the back wheel while the other was on the ground and the car
was in gear.  it behaves like a spool, or welded spiders.

It may be a week or so before I can remove it, so I was curious what could
be in there.

Thanks

Chuck P
65 Midget
69 Midget (parts car)
46 Willys CJ2a
http://home.off-road.com/~chuckp