The ford taurus fan seems to work for everyone. I have one and it works fine. Be aware that it draws a lot of current though.
Yes, the 700r4 from 84-87 were the worst ones.
'76 up radiators will accept the Taurus/Sable/Contour fan pretty well, but the older jeeps have narrower radiators and don't do as well.
I used a Hayden fan on one side, and a '89 Cadillac fan on the other (one pushes, one pulls, and I have Redundancy in case one fails).
The Contour fans I've installed I split the current load/service to the fans.
That way each fan has it's own current supply, breaker, relay, ect.
The idea was REDUNDANCY, so if one relay or breaker quits, you don't loose BOTH fans at the same time, and you have a chance to 'Limp Home' if one goes...
Use SELF RESETTING breakers instead of fuses!
That way, if you get into deep water or something else that slows the fans down, you don't wind up with a blown fuse and the fan not restarting...
Breakers will allow the fan to start up on it's own again, and they will do it several times before they give up.
One temp switch can EASILY be wired to control both power relays, and I don't see much wrong with this if you want both fans to come on at the same time...
(High current draw all at once, but that's a non issue with dual breakers and dual relays)
Two temp switches if you want one fan to start sooner, then the other to come on as the temp rises...
Or if you want a 'Soft Start', where both fans don't come on at the same time and demand a bunch of current all at once.
I would consider a 'Cut Out' switch if you do deep water or mud.
I have a switch on the dash that turns my fans OFF on demand, like when I'm deep water fording...
(Trying to move water will make the fans burn up if you don't have protection like a properly sized breaker or cut off switch to stop them)
I normally switch the GROUND to the relay instead of the power... (most people switch the POWER to the relay)
By switching the ground connection, if the wire rubs through or gets pinched, the fans simply stay 'ON',
If the power wire is grounded or interrupted, the fans DO NOT WORK at all, and that can be BAD if you don't have a warning light/buzzer to tell you there is something wrong with the cooling system and the engine is over heating!
Not many people I know watch the gauges or idiot lights when wheeling... And I'm no exception, so I wired in a buzzer to alert me when things go wrong!
The early 700R4 transmissions had problems with a sprague clutch, reaction shell, and front pump.
All these were corrected by the late '80's and the transmission is a work horse when those problems are corrected...
DO NOT LUG the transmission in OVER DRIVE!
If you tow a heavy trailer, take it out of OD when towing!
These things build MASSIVE heat when in OD and heavily loaded...
If you decide to try a 4L60E, remember, with very little wiring you can have TAP SHIFTER buttons in the steering wheel!
Nothing like Up/Down shifting simply by tapping a button in the wheel! Saves a ton of time and effort when you are busy wheeling!