I am a bit confused by what I see in the way of generator heads.  What is an "ST" head?  Is it a type of head or is it a brand name?  I did a search on ebay and found some 1800rpm heads that are blue and some that are grey.  Anyone familiar with either or both of these types?  Any info will be appreciated.  I have been following this forum site for a while now and am becomming very interested in getting a large twin like a 24/2 or larger if available to power a 20KW 1800rpm head so I can run my whole house during an outage.  I already have a 200A manual transfer switch installed, but my little 5kw generator will not run my clothes dryer or my oven and it will just barely run the water heater if I turn off everything else.  So a totally cool looking Lister-type diesel gen-set would certainly fill the bill.  (and my dad will think I bought a John Deere when he hears it!!!)  Any info on these gen heads or where they are available will be much appreciated! 
Thanks!