oil loss

Hello everyone, First post here, after scouring forums I can't solve my problem so I hope I can find some help here! I drive my Dad's/Boss's 02 7.3 f250 4x4 single rear wheel auto w/ 130000 km(80000 miles). It has no mods and we have never owned a diesel truck prior to this one which we bought...

My 01 7.3 has been running perfectly for years now and yesterday it seemed to torpedo. Pulling small trailer on highway I started to notice whiteish smoke, stopped, checked and it smells pretty oily. Really bad at idle, seems to clear up at acceleration. Limping it home oil pressure dropped...