Tranny fluid change 99 Ext 5.3 LS

OK experts... I've searched for this and didn't come up with anything which means the answer is right in front of me - people always hides things there on me...:banghead:

It's time for a fluid change and the shops won't assume any liability for a flush on a unit with 163k miles on it since it would be the first "flush" done. The questions: Is it at all possible for ME to drain any more fluid than just what is held in the pan and if so how do I go about it? Oh, I'm dealing with the push button Auto Trac 4x4 also.

I've never worried about it in the past and just drained the pan off but if I can do a more thorough job of replacing old fluid I'd like to this time. Thoughts?

And while I'm asking, anyone know of a source for JUST the PCB that goes into the Auto Trac dash module? I've already soldered the board once and it's beginning to act up again. If I don't have to drop $60 for a whole new unit and can simply replace the PCB I'd rather do that. Possible?

how nasty is the fluid? changing the filter and cleaning the pan is not a bad thing. should be about 5.5qts. just pulling the pan. if the oil is not roasted and you have no other tras. concerns other than maintenance i would swap the filter fill with the cheapest fuild i could find and go straight to the full synthetic flush place.

Do not have it flushed,a huge no no.It is not worth the money,you will have a valvebody cleaning done if you do this.My father knows a guy that has his own transmission shop that does valve body cleanings because someone had the transmission flushed.Changing the fluid and filter is the best thing to do.Do not throw out the pan gasket away if it is a reusable pan gasket.Most GM transmissions have a reusable pan gasket.

one thing you can do if you have a drain plug on your transmission pan is to drain the fluid, fill it back up, start and shift through the gears for a few mintues, drain the fluid, and do it all over again until it comes clean. this usually takes about 16 qts. then when you get it where you want it, drop the pan and change the filter and fill it back up, shift through your gears again to make sure everything is full, check the level and your done. i work at a shop and we have used this method on a few different vehicles that are very hard to hook a machine up to. it would be a lot cheaper than goin in and having it flushed.