Older model stihl 039

[Chrisobees]

Hi everyone, need some advice on a older model stihl 039, wanting to change the carb out to the newer style air cleaner ( the air cleaner with the slot in it) currently it has a Walbro HD-5 on it. The part list says there are like 3 different carbs for it. Hd21b, hd18b,and a hd19b. Can any one recommended a carb that's fully adjustable, and would be the same jetting, as I do notice that they also suit the 029.
There is a hd19 on eBay,but according to my part list the jets are different to the hd5. 
Thanks in advance from Australia.. 

[johndoggie]

I am also curious to this as I have the same saw.  Are the newer style carbs with the red High/Low fuel screws adjustable for the mixture?  I purchased one and looks like they cannot be adjusted.  I use mine from 3000 ft to 10,000 ft and need the adjustment.  
My current carb is fully adjustable, with no oval vent tube to the air filter.
-John