mcivatte

I have two 1999 GMC Sierra 1500 4x4 with the 5.3. The motor is locked up on one and I have been using that truck as my parts truck. On my other truck I have a crack bellhousing. My plan is to swap bellhousing but the flywheel is locked on my parts truck due to the motor being locked, making it so I can not get to the torque converter bolts. My question is.... Is there another way of dropping the transmission and getting the bellhousing without taking the motor out. I read that I could drop the oil pan and see if I can unlock the flywheel somehow. I'm lost guys, I am a YouTube mechanic and I really haven't found much online. Thanks in advance.