I have a Colt AR-15A3, and a A1 fixed stock to replace the collapsible one. Do I need the newer wrench with 3 notches or the older one? I am not a super tech guy, and honestly can not tell by just looking, lol.
S/F
Flyingrhino

look at the retaining ring.  How many holes do you see? one or four?

In either case the wrench with one tooth will work, but with the newer rings with four holes, the wrench with 3 teeth may make it easier.

Vinnie,
Thanks for the help. It has three small indentations (stake marks?), and two small holes, one at about 10 o'clock and the other at about 5 o'clock.
Flyingrhino

hmm if it's staked, it's going to be a bitch to take off.

OK let's clarify this.  I just looked at two of my AR's, both are Bushies.  

My Post ban bushy with the telestyled stock is the newer ribbed "M4" stock.  It has 4 rectangular holes on now side and three smaller rectangular "cut outs" (lacking a better description) on the other.  These are not stakes.  For this type of retaining ring, the newer 3 toothed wrench will probably work better, allowing you to apply your energy to more or the ring.

My other Bushy is a Pre ban with the older type "CAR" telestock.  It's ring only has one round hole in the middle of the ring, in which case the wrench with one tooth will work fine for this type of stock.

Again, in either case, the older wrench will work on both types, but with the newer ring, the newer wrench will be more effective.