Automatic transmission reliability for 98 2.7 liter, how long do they last?

I have this friend who is a great mechanic that I respect a lot. I have had a 2.7 auto extended cab Tacoma for about 4 years and he finally picked up a 99 standard cab Tacoma this last year that is manual transmission 2.7 (after going through 14 other vehicles). He is always harping on the fact that a manual transmission will last longer. I have 81k on my truck. I changed the auto transmission oil last year. I tow quads once a month, but nothing near the weight limit. I recently became interested in driving in the sand.
How long before people usually have to replace the transmission?
Are there any tips for maintenance to increase transmission life?

 

I had a 98 Tacoma reg cab 4x4 auto 4cyl with 203k miles on it and the trans still shifted fine. At 180k I had to replace a shift solenoid which took all of 45 minutes... There tough.

 

Like 20 million miles lol no a long time.