Drive / Half Shaft dust cover missing

[elohim_imanu]

I am upgrading my diff, doing a 5 stud conversion and putting on GTST brakes and I have noticed that the 5x1 half shafts I purchased off a wrecker seem to be missing a dust cover or grease cover. Do some models not use it, or are mine just missing? Probably a good idea to have them there I would think. Or do some models have a rubber seal that is supposed to be in the knuckle/carrier. There has been something there, as it is all nice and polished. I realise there is a seal on the vertical face but not on the circumference. 

Left is the "new" 5x1 and right is my old 3x2 half shaft. with the said cover.

Does anyone have any suggestions what I can do. Does not seem to be a part number associated with it.