Wow!! I'd be a rich dude if I could get 2 grand for a 4L60E rebuild. A fair price to pull it out, rebuild, 1 year warranty, with a beast sunshell, vette servo, and small shift kit should be around 1400-1600. The kit is less that $150 dollars. You can put everything in it bulletproof for 2000. This is the most common transmission out there, parts are easy to find and pretty cheap. I would shop around. We have about 6-7 shops within 30 miles of ours, so competition does keep the price down a little, but $2000.00 is too high. Heck last I checked you can get a GM Reman with a 3 year 30 thousand mile warranty for $1200. I did 4-4L60E's this week, all were under $1400 installed after tax.
The rattle in the dash is most likely the torque shuddering.