Feeline,
You don't say what the exact generator you have is. I'm assuming, from those model letters, it's an Onan, either 7.5 QD or, an 8QD, quiet diesel generator. I really can't speak for the 8K unit but, I've got some time on our 7.5QD. I've had it about 2/3 of the way torn down for various repairs and replacement of parts. But, as for your changing the fuel filter on yours, if it's anything like ours, it's a piece of cake.
If you haven't seen one, the filter is a rectangular piece, about 3"x4"x 6" or there abouts. It takes a coupleof wrenches to loosen the fuel lines to it and, if I recall, there's a bracket that holds the whole thing in place. It's been a while so, I might be off a bit here but, not too far.
Access to it, is from under the generator itself. There's a door, towards the drivers side that must be removed in order to gain access to that filter. You'll see what it takes to get that door out of the way. A hint here, if you take on this little project, have some rags ready. There's good possibility that you'll have some diesel running down your arm. Not much but, it's nusence.
And, once the old filter is out, and you start to install the new one, do not tighten either of the lines until both are well threaded into their fittings. Then you tighten them and then, lock it all back into the bracket.
Then, start the gen up and check for leaks. Once no leaks are detected, then you can put the door back on the bottom.
Scott