TooMany62, excellent post. I dug in and have some examples I found in the research. First the "standard" most of us have tried or used:
Hayden 2765
Overall Height 2.67"
Standard Clutch - 60-70% Fan turn when engaged.
Use with 1 1/2" pitch fans
Here are some heavier duty alternates that are 5/8" to 15/16" longer:
Hayden 2747
Overall Height 3.34"
Heavy Duty Clutch - 70-90% Fan turn when engaged
Use with 2 1/2" pitch fans
Hayden 2797
Overall Height 3.65"
Severe Duty Clutch - 80-90% Fan turn when engaged
Use with 2 1/2" pitch fans
On my E-Body, I could easily fit either one into my application but the 2747 would be a cleaner fit. This would give me 10-20% more volume at idle plus it would put my fan deeper in the shroud where it needs to be. I could possibly fit the 2797 which would give me 20% more volume but I may be a tad too deep.
If the solid fan works for me, I am going to measure again to see how the severe duty would fit. All three clutches are available locally so it would be a great test.