Excursion diff fluid? Swapping

[wckdpowerstroke]

Ok finally joining the ex crew. Trading my 99 reg cab 7.3 for an 03 ex. I am removing a bunch of parts to swap over. Im taking my diff covers

My ? Is- when i changed them 10k ago i put royal purple in them. Do you think id be ok pitting the royal purple back into the excursion. Obviously ill have a clean catch pan to do so. Or should i put new back in the ex and use the old royal in my trade in?

Thanks
Mike