both cost about the same to rebuild to take say 350-400hp
the 700 has a very low first gear, useless with rear gears like 3.73/3.90/4.11/ unless in a truck that has tall tires.. car tires in the 26-27" tall. it becomes a very short 1st gear.. and the jump to 2nd is a biggie..
the 2004r the gear spacing is better.. better o/d gear %
the 2004r if replacing a th350(short tail) is almost a bolt in..
you have to move the crossmember back some,, but you use the th350 drive shaft..
the 700r4 will require a shortened shaft..
both require the t.v. cable and correct bracket on the intake