That was my thinking, these trucks are stupid simple, and I like them because of that. Eliminating the cooler that seems to drop pressure and leak from the lines frequently means I have one less thing to worry about failing. I run Rotella T6 and good filters, usually with Archoil AR9100, a...
You are probably right and I suspected that as well, the gasket just fell right out and it looked like it was leaking internally, but I couldn't afford parts to rebuild it and get new lines anyway. One less issue to deal with either way, in Texas we definitely don't need an oil warmer! Haha
I was a bit paranoid deleting the oil cooler, but the lines were seeping and they appeared to have been replaced recently. It also seemed low on oil pressure at hot idle.
I used a melling oil filter adapter for a typical 350, and a Bosch 3322 oil filter. The bolt size is 5/16"-18x1-1/4"...