Manual Transmissions

Early Bronco Manual Transmission Options

These days there are many options for manual transmissions in your early Bronco. Originally, a three-speed column shifted transmission was the only stock transmission option for 66-72 Ford Broncos and the only manual transmission option in any 66-77 Ford Bronco. There were various versions of the manual three speed. They were all "top loaded" type transmissions. They are commonly referred to as RAT, RAN or HEF. Today, many of these transmissions have been swapped out for more capable 4-speed and 5-speed manual transmissions. The most popular early Bronco 5-speed manual transmission swap today is the AX15 due to its pricing, availability and relatively simple installation process. <
Transmission Gear Ratios
  1st 2nd 3nd 4th 5th
RAT 3-speed (Stock) 3.41 1.86 1.00    
RAN 3 speed (Stock) 2.99 1.75 1.00    
NP435 4-speed Transmission 6.69 3.34 1.79 1.00  
T18 4-speed Transmission 6.32 3.09 1.69 1.00  
AX15 5-speed Transmission 3.83 2.33 1.44 1.00 .79
NV4500 5-speed Transmission 5.61 3.04 1.67 1.00 .73
NV 3550 5-speed Transmission 4.01 2.32 1.40 1.00 .78