e240 frt diff stuck in oil pan

[dvsgn]

hello, first time posting here .am gm mechanic but doing 2004 engine re & re for overhaul(machine shop is rebuilding) , on an all wheel drive 2004 e240 6 cylinder gas engine. took engine out and can not seperate the front differential from the oil pan . I have taken the intermediate shaft that goes
thru the pan , but the diff will not seperate. any ideas,anyone been there.
this car only has 50000 kms on it . was a leased unit and never got much TLC.
Engine getting rebuild rebuild because it blow smoke out the exhaust like crazy at time when accelerating. i think the rings are stuck . thanks