I don't want to sound too cynical, but again follow the money. The 5th generation was a body style change but I doubt Toyota spent money to redesign and change the running gear. And that is proven out if the '09 and '10's both have the same problems. That said it is way cheaper for Toyota to address the new models only, as they are the ones being sold now.
And yes I have had the 4/R to two dealerships, with comments ranging from 'we have not heard anything about this' to 'Toyota does not consider this a problem' and 'don't believe everything you read on those blogs'...
Thanks so much for you help and I'll check out the 4th generation board.
best regards
Here is one thread on the 4th Gens discussing it.
http://www.toyota-4runner.org/4th-gen-t4rs/68581-tsb-tranny-lag-apply-4th-gen.html
It's the software programmed into each model for the ATC(Adaptive Transmission Control) systems that people complain about.
The Adaptive Transmission Control system commonly called a "Learning"transmission recognizes individual styles of driving (e.g., aggressive vs. Relaxed) and adapts transmission shift parameters accordingly.
The software for the 5th Gens ECM is different then the 4ths but the A750E(2wd) and the A750F(4wd) are the same transmissions used in the both.The ECM won't allow 5th Gen software to be flashed on to a 4th Gen. though.
The same Torsen T3 center diff that was used in the 4th Gens is used in the Limited 4x4's but the part time transfer of the SR5/TE is new to 4Runners.On the Limiteds , still trying to figure out if the 4L unlocked is a software change or a mechanical change in the Torsen's for the 5ths.
I noticed a lag in the first 1000 miles of mine when I was taking it easy during break-in. After that I reset the ECM(took the neg battery cable loose overnight)and started driving my normal lead footed style the shift points became alot more crisp and not near the lag between shifts. Although it still has that hesitation when I'm going R to D like when backing out of a parking space but that's probably programmed in to protect it.Nothing harder on a tranny then going from R to D without coming to a complete stop.
It's not the trannies.The A750 transmissions are practically bulletproof and are used in almost all of Toyota's trucks including LC's ,Lexus's and Prado's since 2003 and are one of the most reliable trannies in the world. They are in +500hp/660ft/lb factory TRD supercharged 5.7L Tundras so they can hold anything a 4Runner can throw at them.Toyota doesn't make the transmissions,another Japanese company named Aisen-Warner makes them for them and there are literally millions of them around the world being flogged daily in Toyota trucks.
Here's some tech info on A750's for people ,like me, that are into that sort of thing.It's from a Tundra but 4runners use the same ones.
Toyota A750E and A750F Transmission Tech Info