a TCI 700r4 is 1500$ I believe. And thats rebuilt with high performance clutches and an upgraded torque converter. The same th350 is 900$. So there is a difference in price, but the overdrive is nice. My GFs 3rd gen camaro has a super high first gear, its a 2.8 with 135 hp and its faster than my 150hp cobalt till about 40 mph, it will still lay some rubber, and at 60 mph, it cruises at 1700 rpms, which still leaves room for a higher axle ratio. and it will get 24 or 25 mpg running around town with a lot of stop and go and 40 mph roads in there. So im sure it would be similar on a supra. The problem with 700r4s is poor owner care. The trans fluid breaks down over time from heat and age and clogs up the torque converter. This lowers the pressure the trans has to squeeze the clutches. Then in overdrive the clutch will slip, allowing it to get hot, the fluid starts to break down when it gets hot, and it starts a chain reaction which eventually fries the OD gears and the rest of the trans down the line. And that can all be avoided by changing the fluid on time. The best trans to get would be out of an 80s or early 90s gm truck or van with OD. They have 700r4s with heavy duty TCs, clutchs, and come with a higher first gear. and also a nice trans cooler would help it out a ton.