So I've read through the excellent sticky write-up on how to do this. Being a new owner with 125k mi on the truck and unknown last trans flush, 1) should I flush, drive a week and flush again? and...2) if so, change filter after first flush or second flush? thanks...

 

Check out this thread I started about a month ago. Only four feedback/replies, but thought you should read it, given the mileage on your disco.
You'll have to cut and paste the link into the forum search engine and my topic should populate. Have a read and then decide about what to do about the filter thing.




Do you agree about tranny filter replacement?

 

I did 4 transmission fluid changes with about 100 miles between changes. Since you can only drain about 1/2 of the total capacity of the tranmission fluid, 4 changes will replace approximately 94% of your transmission fluid. Changed the filter on the last change. My vehicle had approximately 120,000 miles at that point.
BTW there is a couple of magnets in the pan that'll get most of the fine metallic paticles in there.