There are so many switches these days that I can't keep up... But I looked it up:
Alpaca switches, like several switch types these days seem to be made by Durock, and there are two variations: regular linear and silenced linear. Both have bottom housings of Nylon and gold-plated springs with 62 bottom-out weight.
I'm not sure what else makes these different from other Durock Linear and Durock Silent Linear switches though ...
Silencing is done by rubber bumpers on the slider. If it is the Silent version of Alpaca that you prefer then I'd suggest getting some Gateron Silent Red with opaque Nylon housings and combining them with 62g
Sprit springs to put into them. Then make sure that they are well lubricated. Sprit also sells lube at his own store, but lube and Sprit springs are also available at other stores that may have other things you want.
(BTW, Alpaca Linears added to the Wiki. People who care, by all means do add other Durock variants! The Wiki is open to editing to all registered users)
. But anyways I have Gateron Yellow switches in my keyboard right now and was wondering if I could turn them into alpacas by using different housings and stems. Also I really like the sound of Alpacas and if you find anywhere that sells them then let me know. I might call these "Gateron Yalpacas" or something like that. From what I see they use Cherry Housings and POM Stems, also I heard that Gateron Yellow springs work fine and that I might not need to change them, any thoughts. (hope you guys aren't as shitty as the guys over at r/MK 
)