I run the 200r4 from Bowtie Overdrive and the benefit over the 700r4 for me was I didn't need a adapter for the bellhousing and I didn't have to shorten/replace the driveline. That was with a 2 spd ST-300 and not a TH400 though. I'm not sure if you would have to swap out the tranny yoke. Plus the 200r4 was a little cheaper than the 700r4. The 1st to 2nd gear ratio is a little closer to.