NP435/T18 4-speed to Dana 20 Adapter, 66-77 Bronco SKU: 8318

Early Bronco NP435 to Dana 20 Adapter

This adapter kit will allow you to adapt a New Process NP435 transmission into your 66-77 Ford Bronco with the factory Dana 20 transfer case. This adapter kit is designed for use with NP435 transmissions out of Ford F100, F200, F300 & 1-ton trucks with the Ford small block bellhousing bolt pattern. The Ford transmissions will have a 8.5" x 6.25" bellhousing pattern with a bellhousing pilot diameter of 4.848". This adapter is designed for 2WD 28-spline output shafts with a 5.5" to 6" stick out. The bolt pattern on this adapter is for the 2WD NP435 transmission which has a square bolt pattern.

The NP435 4-speed manual transmission is a popular transmission swap for the early Bronco due to its low granny first gear and durable construction. The first gear on the NP435 is an ultra-low 6.69:1 ratio, making it great for rock crawling. Second gear basically matches right up with the factory early Bronco 3-speed transmission first gear. The NP435 second gear ratio is 3.34:1 and the early Bronco stock 3-speed first gear ratio is between 2.99:1 and 3.41:1 depending on whether it is a RAT or RAN transmission. The NP435 transmission was found in many 1966-92 Ford trucks from 1/2-ton to 1-ton.

This adapter kit will also work with T18 4-speed manual transmissions which came in some 68-82 Ford F100-F250's. The T18 transmission setups are about 1-inch longer than the NP435. Typically, no driveshaft modification is necessary with an NP435 setup, but with T18 transmissions slight modification may be required.

NP435 4WD transmissions will have an A-pattern bolt pattern where the lower two holes are farther apart than the upper two holes. For use in the 4WD version, the upper two holes will need to be added to the adapter to match the NP435 pattern. Additional modifications are also necessary to use the 4WD transmission, so we suggest looking to source the 2WD version for ease of installation.

NP435 4-speed Manual Transmission Gearing

• First Gear: 6.69:1
• Second Gear: 3.34:1
• Third Gear: 1.79:1
• Fourth Gear: 1.00:1