Thanks Trust Thats funny one set of drawings show M3 and the other M4 , I have emailed a few people so hope to find out what they are but it all standards WR75 flange , I may not have to use them if I can get the old ones out but from past experience they will shear off . I wont be using the old corotor or old LNB so best I leave it all together . Because if it shears off I will need a pillar drill to drill it out then retap the hole so best I find some new screws . Depth of screws seems to be 5.2 and O ring size seems to be ok . Yes I would think it would be the size for all WR75 Flange LNBs .