There are two types of transmission on a 2004 Toyota Tacoma: 5 Speed Manual, or an automatic transmission. Depending on your preference, you can purchase/request the transmission that suits your needs.
The 2004 Toyota Tacoma has double overhead cam (DOHC).
R134a
Dextron III
I have a 2000 Tacoma 4x2 and it uses Dextron II. Pull out the dipstick where you check the trans fluid level and it should be stamped on it.
Toyota ATF Type T4 This fluid supersedes all other fluids.
Depends on what year, look on the dipstick. And if it doesn't have a dipstick, it uses WS fluid.
The 2014 Toyota Tacoma has double overhead cam (DOHC).
The 2013 Toyota Tacoma has double overhead cam (DOHC).
The 2012 Toyota Tacoma has double overhead cam (DOHC).
The 2007 Toyota Tacoma has double overhead cam (DOHC).
The 2009 Toyota Tacoma has double overhead cam (DOHC).
The 2005 Toyota Tacoma has double overhead cam (DOHC).