If you pull one pull em both. You should be alright, but it is better to just pull the internals out and put the housings back in to act as a restrictor so you will get better water pressure. The diaphrams have to be in great shape for the system to work as everything is based off of water pressure. And just because the impeller looks good, doesn't mean it is. I couldn't tell you how many brand new ones I have changed out for overheating, and the new OEM impeller fixed it

Thanks guys, I pulled the stats and ran all day yesterday without an issue. Did a lot of cruising and tubing and worked the engine pretty hard. I will be ordering a couple of new stats asap.