Sorry for not replying sooner, life got busy and other things came up, etc...could definitely be from the cooler. there's not really enough stuff there to say that something is currently making metal IMO. It's natural for the gears to shed metal, as well as bronze show up from bearings.
i think my previous post got cut off, but I weld a nut in the pan and use a GM drain plug. if you have a shallow oan the factory deep pan is a nice upgrade too, make sure you use the correct filter.
PS: glad to hear everything is still working good. are you still happy with the shift firmness?
I have the deep pan. Thanks for the tip about welding a nut on it. I don't have a welder but I believe I can arrange something for the next fluid change.
As for the shifting,
Everything shifts nice and smooth, only when shifting into 3rd gear it makes a noticeable hard shift. If I remember correctly you said it is better for the longevity of the clutch packs. It is not crazy but always surprising as that is the only time it makes a hard shift.
I guess it is how it is now as there is not much can be done about that now.