Yes...posi or not posi?

[Siedl]

I've been reading through previous threads regarding g identifying posi, locked or open. Reading so many different explanations there are discrepancies and I need to be clear on the rearend I have.

I am pretty sure it's posi but could be locked...

Jacked it up. Spun the one tire; wheels move in opposite direction. Spun the pinion yoke and both wheels turn the same direction. (That's my clue it's posi) but when I take the cover off there's no spring in the middle and I don't see or can't identify the clutch plates.

1. Am I correct that spinning the WHEEL does NOT determine posi, or not?
2. If spinning the YOKE both wheels turn the same direction AND there is no spring under the cover is it for sure locked?
3. I have the number from the ring gear but can't find the decoder for it.
40 13 gm c (5or6) z11 721

Thanks so much! Love you guys!