SMOKE SMOKE cloud

[nrwhite]

had this 96 f450 (180k miles on it) for about a year. hardly hardly use it. about 2 months ago, it was about a 40degree morning. started and there was big hissing. since, i have find out that that's ok - helps the engine warm quicker. but major major smoke cloud has happened since. white-grey (noxious - not water) smoke billows out of the exhaust which makes such a cloud that big rigs have to hold back behind me. it does not go away and just smokes and smokes. i opened the hood and there was some smoke coming out of passenger side at turbo. the clamp there was really loose so i tightened it but made no difference. also, masses of smoke from drivers exhaust manifold. had the gasket at the manifold replaced ($300) and the smoke is still there. the mechanic said there was a lot of oil in the turbo but that he thinks it could spin by hand. from my search, i can only guess it could be
1 injector o-rings
2 turbo o-rings/seals
3 turbo is broken and needs to be replaced.

the truck starts fine, pulls ok but has a rough idle.