Jeff,
The manuals for 20-30 and 25 both say to remove engine and gearbox as one. I have only the experience of pulling my 20-30 but having done that I think if you can just pull the engine alone there would be a good chance of damaging the gearbox input shaft or clutch linkage.
On the 20-30 it is suggested you have the back wheels off the ground so that they can turn allowing the gears to disengage as you pull the engine/gearbox assembly.
What I didn’t understand was having the engine and gearbox dangling from my hoist how was I to separate them without doing some damage.
I took two 8 foot long 6x6 fenceposts and some angle iron and made a frame with the inside dimension between the angle iron equal to that of the U frame. With two other offcuts of 6x6 at each end the frame top is about 18 inches off the floor. I made cutouts for the shafts that stick out each side of the gearbox.
I greased the angle irons and having un-bolted the engine from the gearbox slid the engine forward.
This has been a very useful workbench used throughout the restoration of the engine and gearbox and a good height for working. The last photos show I am ready to reconnect the engine to gearbox and put it back in the frame.
Alan Painter, Brownsville,Oregon