CM2250 coolant in oil after being jacked up high on front tires

[Kingcali111]

Hello community members, I got 2013 Cummins ISX, I took the truck to get dyno done, it came out good. Then I jacked the truck up high by wooden blocks under the front tires to put the PTO on and unfortunately due to family issues, I wasn't able to drive for 4 or 5 month, so all these months truck was sitting on the blocks, and I recently finished the PTO, before starting the engine was doing a regular check for coolant/oil levels, saw the coolant reservoir is empty, checked oil dipstick and it's all milky, drained the oil pan, all coolant is mixed with oil.

Now I don't understand, the dyno came good and after I jacked the truck up high the coolant leaked inside, what could be the issue here, so puzzled what could be wrong here, any help is appreciated.