Yamaha with Mercury prop thrust washer difference

[Daf290]

I have a 2000 Yamaha 150 VTLR model (2stroke) with a Mercury Tempest Plus prop. I have a new hub kit and the thrust washer is different between old and new, the old one is flat against the motor lower unit and the new one is designed to fit deeper into the lower unit.
Can you please provide advice on which unit to use? New one looks like it would do a better job of keeping the seal in place if this is an issue. No problem using the old one as far as I can see.
Photo of both attached
Thanks!

[21XDC]

You can not use a yamaha thrust washer on the merc props. It does not mate to the "merc prop" hub.

You need the flo torq hub kit for yamaha motors. The thrust washer is thicker than the models for mercs.

[Daf290]

This is the hub kit that I have, I believe it’s correct. I am still not sure if I should use the old or new thrust washer
not actually certain what the thrust washer is designed to do? Only support the hub on the prop side or also apply pressure to the lower unit seal?

[21XDC]

Use that one....