Formula used-
rpm x tire diameter / trans gear ratio x axle gear ratio x 336 = mph

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1st gear at 600rpm...

Bronco-
ZF +  29" tire + 3.55 axle = 2.6 mph
ZF + 31.5 tire + 3.55 axle = 2.8 mph

'75 F150-
T18 + 31.5 tire +3.50 axle = 2.5 mph r2.2
T18 + 31.5 tire +3.25 axle = 2.7 mph r2.3

ZF  1st = 5.72 = r5.72
T18 1st = 6.32 ~ r7.44

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2nd gear at 600rpm...

Bronco-
ZF +  29" tire + 3.55 axle = 5.0 mph  <--free Daytona's :/
ZF + 31.5 tire + 3.55 axle = 5.4 mph  <--will be good with its lower weight? 

'75 F150-
T18 + 31.5 tire +3.50 axle = 5.2 mph  <--real nice, not too slow and not too fast for its weight :)
T18 + 31.5 tire +3.25 axle = 5.6 mph  <--old setup, felt on the edge of too fast for its weight :/

F250 parts truck-
ZF + 31.5 tire + 4.10 axle = 4.7 mph  <--stock, too slow when empty but good when loaded or towing?

ZF    2nd = 2.94
T18   2nd = 3.09
Mazda 1st = 3.91
Mazda 2nd = 2.24

Mazda 5 speed close ratio-
Mazda + 1st +  29" + 3.55 = 3.7 mph
Mazda + 1st + 30.5 + 3.55 = 3.9 mph
Mazda + 2nd +  29" + 3.55 = 6.5 mph
Mazda + 2nd + 30.5 + 3.55 = 6.9 mph

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3rd gear at 3200rpm...

Bronco-
ZF +  29" tire + 3.55 axle = 48 mph 
ZF + 31.5 tire + 3.55 axle = 53 mph    

'75 F150-
T18 + 31.5 tire +3.50 axle = 51 mph
T18 + 31.5 tire +3.25 axle = 54 mph

ZF  3rd gear = 1.61
T18 3rd gear = 1.69

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4th gear at 2600 rpm...

Bronco + Ford8.8-
ZF +  29" tire + 3.55 axle = 63.2   <--same as '91 F150 in 3rd with E4OD off, seems low geared
ZF + 31.5 tire + 3.55 axle = 68.7   <--this is what I will end up with

'75 F150 + Ford9inch-
T18 + 31.5 tire +3.50 axle = 69.6   <--new setup, good in town :)
T18 + 31.5 tire +3.25 axle = 75.0   <--old setup :)

ZF + 31.5 tire + 4.10 axle = 59.5   <--'90 F250 speedometer gearing: tan= 19 yellow= 7

4th = 1.0 ;)

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Overdrive at 2600 rpm...

Bronco-
ZF +  29" tire + 3.55 axle = 83 mph 
ZF + 31.5 tire + 3.55 axle = 90 mph 

'91 F150 E4OD + 29" + 3.55 = 89 mph

ZF 5th  = 0.76
E4OD OD = 0.71 (locked up)

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Tire sizes...

235/75-15's  = 29"   7" wheel
31x10.5-15's = 30.5" 9" wheel
235/85-16's  = 31.5" 7" wheel
265/75-16's  = 31.5" 8" wheel
255/85-16's  = 33"   8" wheel
H/78-15's    = 28.5"+'75 F150 <--they came new on 5+1/2" wide wheels and were squirrely as hell! :(

pi x diameter = circumference 

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Gear ratios...
                 1st   2nd   3rd   4th   5th    -R-
T18 ===========  6.32  3.09  1.69  1.00  ====  r7.44
ZF M5OD-HD ====  5.72  2.94  1.61  1.00  0.76  r5.72
Mazda M5OD-R2 =  3.91  2.24  1.49  1.00  0.80  r3.39
NP435 =========  6.69  3.34  1.74  1.00  ====  r8.26
E4OD ==========  2.71  1.53  1.00  ====  0.71  r2.18
Clark282V =====  6.99  4.09  2.17  1.17  1.00  r5.89
NV 4500 =======  5.61  3.04  1.67  1.00  0.73  r5.61
T19 = http://www.novak-adapt.com/images/graphics/t19_specs_gasket.gif

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