Bought my filters from my dealer[of course,where else you going to make sure you get the right filters on first change],plus they was about as cheap as any other napa brand or whatever[if you knew the numbers that is.]
But bought napa brand heavy duty universal for trans,dealer doesn't stock oil I don't think anyways,plus when I was there to buy filters I asked him,he showed me a 5 gal bucket or two and they were napa brand,thats why I bought them at napa. I'm sure most other heavy duty type universal is about as good as another?
I supported my dealer plenty when I bought tractor, by the way, I feel.
Used gearoil in front end I bought at a federated auto store,[by the way,that front end on a ck30 tractor anyways,holds alot more than book says,book says,1.19 gal,I've got almost 6 qts in mine now,keeps settling,thats to top of sight glass but not above.]