Omega 2,2 dti Y22DTH Sealing rings Connectors Diesel line

I’m just about to put an Omega 2.2 dti Bj. back into operation in 2001 after a long service life. I’d like to change all the O-rings of the diesel lines (connectors and filter housings), because I have to re-air it after a short service life. Does anyone know the dimensions of the sealing rings? Unfortunately, I couldn’t find anything. The pipes themselves are rusty in the area of the rear axle. I guess these are no longer available, at least I couldn’t find them. How do you help yourself in such a case? Thank you in advance, Ewald