My 4T60E transmission is still good, but in the past I have seen some pieces from the 4th thrust clutch washer in the pan/blocking up the filters flow a bit, it still shifts fine, but at 138k miles I know eventually no matter how much it has been babied, it will eventually need to be rebuilt.
I am no transmission expert, nor do I have the room/tools to properly work on it, so I'll most likely have to pay a shop to do it for me.

My main questions are what is an average price to get the 4T60E removed, rebuilt, and reinstalled?

Are there any special rebuild kits with better rings?
I ask because I recall hearing something in the past, but cannot remember for sure.

Having it rebuilt would a TransGo Shift Kit give the transmission a bit more life?

I'd really love to buy the tranny manual, and maybe a video, so I can do it myself, but I'd have to buy a cherry picker to remove the engine/tranny, as well as a few other tools, and I really do not have a proper space to rebuilt it.

Last question, if it still shifts fine now, would it be better to wait till problems occur, or is knowing that 4th clutch thrust washer is probably destroyed enough to warrant a rebuild?

purchaes de gm transmissions froms de GM autos part is de goods qualaties its nos goes kaput

My car already has 138k miles on it, the motor seems fine via compression numbers I got a while back, and I have replaced a lot of sensors and whatnot, but still my car is only valued at around 1,500.00 at least that is what I am paying taxes on, so I don't want to throw too much money into it, however I also don't want to buy a used car that could end up being a crap shoot.
I got my 96' Park Ave when it had 27k miles on it, and it only had one owner prior to me, an elderly couple, so it has always been well cared for.
I think if I were to buy a rebuilt one I'd be looking at 1,500.00 - 1,800.00, some places charge core fees of like 350.00, I am hoping I could just get mine rebuilt for a bit less, since overall it is still in decent condition.
I can only imagine what a brand new 4T60-E will run me, I'll try to find out just out of curiosity.

Found a site that talks about doing a bit of modifying of the transmission to ensure they last longer, I think these are rebuilt ones as well though.
4T60E: $2675 Yikes, of course that does not include getting it installed.

GM | 4T40E | 4T45E | 4T60E | 4T65E | High Performance AutomaticTransmissions

Hello William, you said it all, at the moment it is still shifting good.
If most of your driving is local, I would wait a while yet. Get the most of it for now.
If you can find someone with a professional/commercial account with GM, your price will be significantly less for the GM rebuilt transmission.
If you are keeping the car, a GM rebuild is the way to go, but all cooler lines etc have to be flushed before install of new tranny.
In the meantime, do a pan drop more frequently, inspect, replace filter & use Dex6 fluid.
The 4T60e shift kit is mainly for the valve body, so no quick fix like the 4t65e.
Throw a can of trans tune in there for 500 miles before the pan drop may help things in the solenoids & valve body quite a bit.

For now my driving is infrequent, and local, but soon I may end up with a job where I drive an hour to, and from work, if that happens I am a little concerned that before long it will be time to address it somehow.
I love the car, and want to keep it for at least another 150k, but I have to take care of things like the water getting in from somewhere, and have my headliner redone, as well as do my front struts before too long, I figure a lot of other bushing are close to needing replacing, but I figured I'd wait till the tranny/motor has to come out for a tranny change before I bother with them, since they are all still ok at the moment..
As soon as I get me a new jack I'll get the pan dropped and replace the fluid with some Dex6, I cannot remember what fluid I used before...