[V8] Distributor Question

[Tom La Plante]

Hey guys, both distributors and the round "sealing plate" near rt.  
distributor have developed substantial leaks.  My 4 binder original  
shop manual doesn't discuss distributor removal(unless I'm just not  
seeing it) and I've never touched them.  I purchased seals from the  
dealer for both distributors/mounting plates/ and the strange round  
plate near the rt distributor(worst leak).  Just wondering if I need  
to find TDC or can just mark and remove and is any sealant required/ 
suggested.  Sincerely Tom La Plante