[texanidiot25]

200R4 is the easiest in that it's the same length as the TH350/400, and depending on what your looking for, many say better gearing (as it has similar gearing to the 350/400). The 700R4 has a very short 1st gear which is awesome for towing, and torque. But it's longer and requires a bit of work moving the crossmember and shortening the drive shaft. Both can be found with mechanical speedos, and both can be built strong for pretty cheap.