I've been through some of this the hard way so here goes. Junkyard sold me ext cab seat for regular cab and then wouldn't take them back so I got educated. Had to find a junk seat to get the "pan"
Crew cab and standard non extended cab seats bolt down the same exact way. The seat "pan" that bolts to the floor and the seats / console bolts to it mentioned above is the key. This also applies to the rear crew cab seats, just consider them front Reg/Ext cab seats.
Extended or Super Cab seats are different due to the need to access the back seat. I BELIEVE this applies to Bronco seats as well. They will not bolt into the 2 other cabs directly.
On the 40 20 40 set up for a extended cab, the left and right seats themselves will bolt onto the std/crew pan. I have done this. However the center console is shaped different on the bottom. I believe (not tried just looked at it) that the metal of the bottom of the console could be reworked to get the SC console mounted up on the Reg/Ext cab "pan". SO, if you have a "pan" for Reg/Ext cab, the SEATS from and Ext cab will work IF MOUNTED ON THE Reg/Ext "pan".
I have a 96 Ext cab that has the Bronco style set up with 2 "captains chairs" and a console you can not sit on. I have never studied if they would fit on the "pan". These brown seats with no tears are for sale if someone in central Calif wants em. No I'm not shipping them. I MIGHT have time to take em out lol.
The 40 20 40 seats, for me give MORE legroom in a std cab. Have one from a 96 in the 86, made it way more livable for a 6'2" guy.
My current seat plan for the 96 crew cab is to get the seat for a luxury level big rig and discard the air suspension and mount it on the "pan" You can get multiple lumbar, massage, and many other. Getting harder to do long miles as old injuries add up, so it is worth the $ to me. We'll see after the engine is in and dialed.