Just my .02, before everyone suggests fan clutchs one thing has to be considered:
What fan are you running?
I used the 2708 fan clutch on my SB cuda with an 18" Autozone fan which is made by Hayden (so says the box in the fine print). If you use a different fan blade it effects the clutch choice as their pitch / offset is COMPLETELY different. My old mopar one was way different than my autozone one so I needed a different clutch. I would of used my mopar blade but I accidently stepped on it and bent it. FYI Factory AC Mopar blades are all over ebay under $20.
I am also running a C body 26" radiator and a 18" fan (almost could of ran a 19" but the shroud offset was a problem). I needed to get my fan blade closer to the rad so the blades were 1/2" of the way in, 2708 worked for my custom application.
Per Hayden online catalog:
2705 fan blade mount to pump 1.53"
2706 1.75"
2707 2.03"
2708 2.32"
I had to use the 2708 with a spacer to fine tune things. I got a spacer pack from Jegs. I had to use the 1/2" one and its really a little too close. The hub of the fan clutch scrapes when going on to the point I pull on the radiator to flex it a little during install. Once its on its 1/2" clearance. The blades are perfectly centered in the middle of the shroud.
So you must determine the blade you are running, the depth in the shroud you want it to be, and measure that to the pump front and do some math and go from there.
ALSO
Autozone clutch "Torque something" is made in China. I looked at it and the casting was thick and sloppy. As far as 71 demon? not being able to find Hayden, that is weird as I got the exact USA made Hayden brand at O-Reilly's for 2 or 4 bucks more than autozone and it was much nicer than the China made Autozone. I also think autozone puts a 93 before the hayden Pn# for their versions but do check.
another guy I know on moparts had this to add to an old thread on this subject (I kept it), he said the following:
"Now ya all need to know the total height of each of these. By total height I mean from where the fan clutch bolts to the water pump to the opposite end, or tip. This is typically called how "tall".
2705 is 3.09" tall.
2706 through 2708 are 3.61" tall.
The Jag 2765 is 2.61" tall. (It actually is closer to 2.75" tall [my measurement] because of the thermal coil tip at the face of the fan clutch.)
These are all thermal fan clutches. Hayen 1705 is 3.09" tall and is a non thermal fan clutch. It fits like it was made by Ma Mopar.
The 2705 through 2708 are excellent fit, as if they were made by Ma Mopar. The Jag 2765 comes with a bushing and has a decent fit. It works, but it leaves a little bit to be desired. People run the Jag clutch with success.
All measurements are from Hayden. All numbers are Hayden part numbers. Some auto store brands use the Hayden part numbers, some don't. But...all of the Hayden part numbers should cross over to any other brand."
and that is what that guy said.
Take it easy
Sean