01Nov2003 (UTC -7) Finally, my auto tranny (2001 UZJ-100 with A343F) doesn't clunk anymore when I'm driving aggressively. I previously thought that it was just firm shifting --which is good as there is less slip on the clutches-- but I was very much mistaken. Now, it's got real good firm shifting, not smooth like in a Camry would --but firm that you get pushed-back-in-your-seat kinda shifts. I looked up the "clunking" (i.e. harsh engagement) symptoms in the Toyota Repair Manuals, and it suggests checking the Accumulator Control Valve and/or Solenoid Modulator Valve. Then I remembered that I recently smelled something that was suspiciously burnt ATF for a while, when I did the nasty Truck Hill and also Five Fingers climb in Hollister Hills in my 6,500lb beast. Add the facts that I haven't drained & refilled my auto tranny and it now has 49,384miles on it, I thought I'd flush and refill the ATF: 1. Drain the ATF via the drain plug 2. Remove the lower transmission pan and scrape off the residue silicone gasket 3. Clean the tranny filter (i.e. oil strainer) at the parts washer 4. Remove the ATF return line from the transmission cooler (i.e. in the radiator), and have a big container ready 5. Note the condition of the expelled ATF. Mine smelt a bit burnt 6. Return the tranny pan, with new gasket. Re-torque bolts as per Toyota specs 7. Fill-up the tranny via the ATF dipstick 8. Start the engine and put it in neutral 9. ATF should now flow to the big container, so continously pour more ATF in until the ATF coming out is nice and clean 10. Between your 12th to 14th quart of ATF, the draining ATF should be clean, so then you can stop the motor 11. You'd need about 2 to 3 more quarts to top it off 12. Check ATF level again later when the engine is warm, just to be sure HTH !!!