Anyone know what the difference is between the different Heavy Breathers for the different Harley Models?

I realise that the fitting plates for the crankcase breathers and venturi openings will definitely be different.

SO....my question is this... Are the remaining parts outside of that fitting plate all identical (ie- elbow, filter etc)?

My reason?

I've bought the missus a Sportster and can find several HB, but all from different models, BUT I can get the Sportster fitting plate seperate from elsewhere to use the remaining HB parts. Is that feasible?

Have a look in eBay - Peter Stevens are selling what you're after for $424 delivered.

I can wrangle the same price (roughly) with a chrome cover worth over $200 which is why I asked about the cross matching.
Not fussed if I can't do it. I'll just buy something model specific like that from Peter Stevens or something off JP's.