done a few...
I've helped drop the oilpan on a few 454 equipped trucks (not factory ones,they were installed by the owners)...depending on the year of the truck,whether its lifted or not,and a few other factors will determine if it will come off "easily"..if you have headers,you might have a harder time..but they do come out without pulling the motor...some trucks have a crossmember directly under the oilpan,some dont..if it does you'll definately have to jack up the engine...
I did the ones I did by removing the motor mount thru bolts,after placing a floor jack under the pan with a block of wood,and jacked the motor up until the bell housing touches the firewall,and put 2x4 wood blocks between the mount thru bolts,(slide them back in temporarily), and the frame mount brackets,to hold it up in the raised position--be aware of the the distributor cap,it can and will shatter if it touches the firewall--best to remove it and lay it aside..also make sure the radiator hoses have enough slack,or you'll rip the bung out of the radiator!
(ask me how I know this!)...and other things like the fan blade touching the radiator,etc..
Sometimes you have to turn the motor over to the #1 firing position to get the crank counterweights out of the pans way to slide it back and remove it..worst part of the job is re-installing the pan without dislodging the end seals and pan gasket..I tie the pan gasket on with string thru the bolt holes,or use silicone to "glue" it on..the end seals I usually use "high tack" to glue them to the pan...but if they make a 1 peice gasket for the big blocks,that would make it much easier--I think Fel-Pro makes one now?...
