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

The physical act of installing the transmission is not that hard. There are a bunch of things associated with a swap like this that take time.
You HAVE to measure the bellhousing runout as it relates to crankshaft centerline. Most of the time you'll need to remove the dowels in the block and use offset dowels.
There can be exhaust system rerouting needed. The speedometer is now electronic, requiring some wiring changes. Seats and carpeting come out. Welding of the floor patch. Changing the automatic brake pedal to the clutch and brake pedals. The installation of the hydraulic clutch setup after measuring to see if the travel will be adequate....