My AW4 swap into a '72 Javelin

The AW4 (Toyota A340) CAN be built to take 425-450 hp. You can get a complete performance built A340 from IPT (Import Performance Transmissions) for around $3k. It will last -- is run behind hopped up turbo Supras. At least the early models used the TV cable, though later ones used an electronic line pressure controller -- basically a servo motor with a link through the TV cable hole in the case that the computer controls. Wouldn't be too hard to lock the line pressure control in the high pressure position. As one of the guys on the Supra forums put it, "you have to hold your foot on the brake harder when stopped" (well, that's close to what he said...).  There are some slight differences between the AW4 and A340, but just calibration AFAIK. Anything that can be done to one should work on the other.  I'd contact IPT first though, as I know the bell is different and the pump input shaft could be a different length or splines, as well as output shaft. Their hi-po rebuild kits and valve body mods will work with the AW4 for sure.

The AW4/A340 is supposedly capable of 450 ft/lbs of torque stock, up to 650 modified (depending on level of modification). The twin turbo Supra guys run 450 hp, but the turbo I6 doesn't produce the torque that a 500 hp 401 would. TORQUE is the issue with a transmission, not hp.  So the trans can be built, and it's not as expensive as it once was. I think 501 Performane was the first US company to build them, can't really find anything on them and the AW4/A340 now, but the Performance Import Transmission site has a lot of info, and the two links below.

If $3K (+ shipping) for a performance replacement trans seems like too much money, you an always go the 2004R/700R4 with adapter route. Probably cost as much or more. I'd start looking for a 5L50/5L60 or 6L60 myself. The more gears the better! Those would probably be a bit on the expensive side though, especially since you would need an aftermarket controller, and the only one I found is $750.

PADDLE SHIFTER!!!   Bear with me a moment as I describe the rotary switch I've used to manually shift my AW4 for years. TV cable is still connected, but no shift computer. The rotary switch works well, you have to manually shift up and down. Put the shift lever in D (or OD if in a Jeep) and the trans starts in whatever position the switch is in. Simple to wire up using diodes for the logic. I have it wired to shift 1-4 with a rocker switch for the lock-up. The trans will not lock the converter in 1st, so I usually leave the lock switch on all the time. 2-3 shift is a bit hard, but if you let off the gas momentarily when shifting it's nice and smooth. The rotary switch works great as long as you have a console with armrest to mount it on so your hand naturally lies over the switch. Two disadvantages -- 1. If no conveniently located console with arm rest it's a PITA as there is no convenient place to mount it.  2. One hand is off the wheel, not good for performance driving. There is no worry about dropping into 1st at speed, or 2nd when in Drive. The trans only brakes in the top two gears -- 3-4 in D, 2-3 in "3" (IIRC that's the next down from D in the XJ). So you an drop to 1st from 70 mph and ride the brake to stop even with the lock-up engaged. I gear down for the engine braking to 3rd then drop through 2nd (even though no braking) down to first at the appropriate speed. That way if something unexpected happens I'm the right gear to get out of the way. If I dropped all the way to 1st from say 50 mph anticipating a stop (safe to do that) and for some reason needed to scoot out of the way, the engine would have to rev way up before the trans would engage due to the gearing for 1st. Going down through the gears I'd be in 3rd and ready to scoot. That's saved my butt a few times!!

I'd never seen this paddle shifter before! The logic circuit will of course work with any two momentary switches, paddles or push buttons. Real neat way to do things! I can't believe I never found it since it's a 2005 thread! But no AW4 reference, and A340 is only mentioned in the text a couple times, not in the subject. I knew Volvo used the trans in the 960, I had a 960 for a few years, but never thought to search Volvo forums!!  The link was found on the Jeep Strokers forum though... don't know how I missed it until now!!

CamJam got one, but I assume it's all about location. Bigger towns and cities may have them more available at pick and pulls and truck salvage yards.  Though I was in the impression like the th400, an aw4 can be converted to 2 wd with proper parts. Just need a good tranny shop to source parts if that is the case.