Suregrip or not?

[koonpup]

So I have a 1974 roadrunner with an 8 1/4 rearend with 2.71 open gears. I bought a 1973 roadrunner that used to have a 340 in it because it had an 8 3/4 rearend in it and got the whole car for $320. So I jacked up the rearend and it has a 489 case. The problem is I can't figure out if it is suregrip or not. When I spin one tire, the other tire doesn't spin at all. When I turn the yoke on the third member, both tires spin the same direction but one is slower than the other. Is it suregrip but worn out or something? Thanks for the help!

 

[tallhair]

Sounds like an open rear to me

 

[mattsmopars]

Sounds the same to me. Most of the time on a suregrip if you turn one tire the other side will turn the same way. You can also leave one side on the ground and jack up the other and try to turn the wheel. If its in neutral or has no drive shaft with a suregrip you will not be able to turn the wheel that is jacked up. If it does spin its a one legger.
Matt