I have a 96 FZJ80 with 150,000 miles, A343 trans. I've noticed just recently that when cold (cold weather as well as my first trip of the day) that the 3rd to 4th gear shift is delayed. I have done 1 drain refill of 3-4 quarts and planned on more until satisfied with freshness of the fluid like some have done here before. 4th gear comes with approx. 3-5 seconds of delay. After the first run through the gears all is well. The trans has no shifting problems- all come smoothly-no reverse delays..etc. I am planning now on a complete flush a la Snow Cruisers FAQ link and I will probably replace with M1. If anyone wants to add there 2 cents, I'd appreciate the input.