hi yea ok i will tke a pic mine must be different but i dont see how its a 99 l seriesI seriously doubt they are longer as if that was the case they would invade the combustion chamber and the piston wouild collide with them. I reacon your thermostat housing is not like the ones fitted to our hippo's. Any chance you can take a photo of the problem area and post it on the thread? Picture says a thousand words as it were.
It seems to me that the only way forward is to release the thermostat housing from the cylinder head. This will allow the pipe to drop out the way and you can get the plug out. The downside is you will have to drain the coolant first.