My Duster is under the knife....TKX going in

Here you go. These are the numbers and work done from the shop. This particular shop isn't the cheapest in the area but I trust them.

TKX 5-speed conversion (replaces 727 3 speed auto)
Technician removed old automatic transmission along with various pieces. Cross-member had to be cut. Transmission cooler lines to radiator had to be removed and plugged. Full interior removed. Exhaust system had to be cut to remove driveshaft and transmission (previous exhaust shop made it one piece). Transmission was mocked up multiple times, measurements were taken and notated for warranty purposes with SST. Trans tunnel was cut and modified, new metal was added and riveted. Sheet metal that came with the kit also had to be reformed. All new metal was painted and sealed to prevent rust. Sound deadening material was laid down before installing new carpet. Interior was fully put back together. Transmission sensors and wiring modified/completed. Clutch master cylinder was mounted after modifying driver fender, primed, and painted area. Bled clutch system. Test driven.
$8,589.65 Note: this included cost of transmission, clutch, pedals and other necessary items.

Transmission Tunnel Sheetmetal Rework and Installation
Install sound deadening mat around transmission tunnel
$900.00

Driver Fender Body Work
Technician professionally modified the driver side fender for clutch master clearance, primed, painted.
$164.99

Modify wiring harness and install speedometer and reverse light connections
Technician had to extend neutral safety switch wire, relocate reverse light wiring, extend and re-wire speedometer wiring.
$150.00

Thanks for posting all of this up!
That's a lot of cash but there's no mystery as to where it went.

It cracks me up to think that I spent $700 on my Dart Sport back in the 1990s and it came with a perfectly fine transmission which (after some modifications) is holding up very well to a 460hp/520lb-ft small block...and I'm now seriously thinking about how I'll save up to make this happen.