To sort of add to this with the first brands supply issues, I am a mobile technician. We work on a lot of semi/ heavy truck class 7 and 8 but also a lot of smaller vehicles that take an ac Delco PF63. The new 6.6 duramax and also the 6.6 v8 gas both use this filter. I bought 4 the other week from one of the largest suppliers of ac Delco parts HUGE warehouse as one of their major brands they even sell ac Delco batteries mainly even group 31.
So I went to buy 4 of the pf63 filters up here and joked with the guy and told him I knew they'd have a lot of them! Local part stores would have one or two or be out of stock with no idea. They had 400 plus pf63A filters back then! I had to actually buy the pf63A filter due to zero availability on the PF63 blue painted filter. The PF63A is black, and the flutes are different on the top so my oil filter cap wrench doesn't fit (and a few other differences).
This week, went to buy more and there were zero. A place bought hundreds from them lol!
I had to special order 10 PF63A from a two hour drive away, it's a regular parts transfer they do daily so no freight/ shipping charges occurred.
Someone with first brands manufacturered the ac Delco oil filter line originally.