I went thru the archives of the Tahoe and Suburban...so realize the '99 1500 Suburban has different circumstances for 2wd, Auto 4WD. Full Time 4WD and Full Time 4WD Low positions.... I launch My boat many times each year, and typically 2wd works just fine.. However I was wondering what would be best and harm the drivetrain the least when I encounter a Very Steep, Slippery or Irregular boat Launch both putting the boat in and out... what do you guys use??

Typically 2wd will be fine, the only time you can damage your drivetrain while in 4WD is when you are turning on a NON-slippery surface, otherwise using 4WD to drive in a straigt line on a non slippery surface will be fine. The auto 4wd will sense wheel slippage and auto compensate for that. So just use whatever you are comfortable with.

Depending on the condition of the launch ramp or what I am pulling out of the water, I will use 2wd or 4wd auto. I have only had to use 4wd low once at Lake Tahoe where the launch ramp had "drifts" of soft sand under water. Couldn't get the boat out of the water in 2wd or auto.
It is pretty easy to leave the burb in 4wd so I use it in rare conditions only.

If it were me, if you needed the extra traction of 4wd, I would use 4hi or 4lo only. My reasoning is, you are sending a tremendous amount of torque to the ground when yanking a boat out of the water. Even though I am sure it can take it, the auto 4wd system has to absorb all this torque when transferring power to the front if slippage is detected. I would not put this stress on the auto 4wd system. Lock it in and let all the power be transferred equally. Thats my thought!

i launch a 25 foot boat in all kinds of lakes here in So. Cal.; unfortunately i'm only rocking a 2wd, and to be honest there have been some times i wish i had 4wd-low.

i don't know how big the boat is, or how good the ramp is, but as long as you have a steady foot, 4wd-low is more than fine. Just remember you're gearing down big time and in doing so you'll have ass-loads of low-end torque at your disposal...use it wisely. I've seen some pretty pathetic stuff around here lately. (it really makes me wonder) :screwy: