Z series 16570 Rolex Explorer 2 or F series?

[zizou18]

Need advice urgently

Getting a preowned explorer 2. Both are in 9/10 condition with cert and box.

Prices are $5500 and 5200 respectively.

Understand that the Z series comes with the newer 3186 movement.

Any comments?

[Oceanklassik]

I'm not sure if all 'Z' series comes with the 3186 movement. 'M' series may be a better bet. Do a 'wiggle test' if you know how to.