I bought one last year for a 400D. Not hard there's a certain sequence to taking the lift pump apart as the pump gears have woodruff keys in them. The seal is just two seals pressed into a sleeve.
The hard part is if the pump gaskets get damaged while taking it apart as they set the end clearance on the pump and scavenge end and the clearance is pretty tight. I ended up making some and replacing the pump bushings. I made the bushings on the lathe.