Yep a 1 year warranty on the transmission, but just like any warranty, they arent with crap. The changes of the going out close enough to the shop is one in zero. Unless you run local never count on a warranty to amount to anything.
2500 is super cheap with the 10 as a core. I would think closer to 3500 maybe 4k for just the transmission with the less valuable 10 speed core
Smaller shops don't gouge you like dealers and big shops do. They also rebuild transmissions themselves instead of making you use oem rebuilt for 3 times the price.
$2500 installed is a smoking deal. I sold a rtlo18913A a while back for $2500 and guy was happy to get it.
No need to replace the rears, you may need to shorten the driveshaft (some models match in length and some don't) and you will need a new shifter head and change the air line plumbing a little to accommodate the splitter. I always junk 10 speeds and install 13 speeds when the time is convenient, it usually takes a Saturday and the shop that remanufactures my transmissions and rear ends for me gives me a full core credit on the 10 speeds if they are the 1600 series. I hate 10 speeds so I would rather change out a transmission a little early at my convenience (saving labor, down time and a tow bill), I get the upgrade done for a lot less than a straight replacement of the 10 speed would cost if done on the road because I broke it on the fly.
Why would that matter? I have pulled every flavor of 10 speed and reinstalled a 13 speed in its place, the only issue that is a question mark is whether the drive shaft length needs to be changed.
Most direct 10s have a 2.64 or numerically lower rear axle ratio. I'm just guessing that's why OP was talking about switching rear diffs.
They will accept it but only for like $700-1000 , cuz my ten speen just went out and im swaping to a 13 and thats what theyre giving me for my core of my 10