Hey man
the spool was in the car when I bought it from Japan and I just had to replace the diff that surrounded it, centre was fine.
I think they are generally cheaper than power lock LSD's like 1.5 and 2 ways but there are down sides. Mostly understeer induced by the diff wanting to go straight ahead. It's damn strong though.
I think I would prefer to have a 2 way but this is what I got and it works for what I need it to do.
I'm not sure if there are different brands or different types for lsd's or vlsd's but I reckon they are all about the same. It just locks both axles together. Nothing fancy about that!