4L65E rebuild/replacement options and cost?

[mackguy]

We had a 99 Suburban totaled by a tree falling on it and are looking for a replacement. We wanted to get something with a little better than the 5,000lb tow rating, so looking for a 6.0 GMT800 platform, and it seems like Denalis are the best way to get this as 2500's seem very few and far between in our price range.

 

So I found an '03 Yukon XL Denali that looks nice, but current owner says that 1st gear is slipping pretty bad. He's priced it pretty aggressively because of this, but I need to have an idea what we're looking at cost-wise to get it taken care of. I've contacted our local dealer and a couple independent shops about a rebuild, but wanted to see what others found here regarding the cost of a rebuild or replacement with a rebuilt unit.

 

Another question I had is whether there are any possibilities to replace it with a different transmission like a 4L80e, or possibly one of the newer 6 speed units. I'm not sure how that would all work out as far as the control system.. just want to consider all the options and costs.

 

Thanks!