Found oil in the coolant.
 

I found oil in my coolant, does this mean it's a cracked block for sure, or could there be more simple issues? I mean cheaper. Pissed.

Head gasket or oil cooler would be my first two suspects

How much oil? Cracked block is a possibility but there are other more common causes that come to mind before that. first guess is head-gasket. Oil cooler is another fairly common possibility.

Could it be Lucas stop leak? I filled it to the top with water and none ended up in the overflow tank. So..

Where and how bad was it leaking before you added stop leak? At this point you probably really need to determine if it is an oil leak. I would say to drain the coolant, refill with water and run a good coolant system flush through the system. drain and refill with just water. then run it for a day or two and monitor it constantly to see if it is an oil leak or just the stop leak. Just don't forget to drain and refill the antifreeze before winter if it all checks out okay.

The previous owner put the crap in there because he didn't want to take the time to cut a hose.. Smh. But I did flush it ran it, still has some stop leak in it but determined it wasn't an oil leak because when you leave the rad cap off and watch the coolant there is no bubbling which is a sure sign of no leak.. However my thermostat for some reason wouldn't open when I started the thing back up and about screwed my engine. So I'm thinking I'm going to ditch the thermostat since it serves no real purpose unless you live in the tundra lol.

Hey Bear, we need you to update your signature so we have an idea of what mods have been done to your truck and if its a 2500, 3500 2wd or 4wd.

I am guessing your headgasket is leaking.

I am sorry I have been posting off mobile. It's the oil cooler, going to get a new one today.