Everything I have read says the engine has to be removed to remove the oil pan. What about if the transmission is out of the truck? I currently have the trans out getting rebuilt and found my oil leak is the oil pan gasket.

 

I got an 03 and I got to swap the oil pump and from what we can see the motor needs to come out.

following this post to see if it's possible.

 

On 4wd Blazers either the engine needs to be lifted or the front diff lowered to get the oil pan to drop away.
Not sure on 2wd Blazers....never had one and never been under one.

 

So. To answer the question, yes, you can remove the oil pan without removing the engine IF the transmission is out. BUT, you do have to remove the oil pump. That is the only hang up.