Adapting a Long Tail housing B/E Body Trans to the A-Body by Dave Clement
When I swapped from the 3 speed column shift in my 68 Barracuda to the long tailshaft 833 OD 4-speed from a D100 truck, the only fabricating I had to do (besides the tunnel extension) was to make a mounting plate that positioned the shifter forward from the rear shifter mount and shorten the drive shaft. Here are the things I found out about this conversion:
1. The three speed bell housing in my 68 Barracuda did not have the correct bolt pattern for the 4-speed and the bearing support pilot hole was to small. I used the bell housing from the pickup.
2. The 3 speed's rear tranny mount transferred directly to the OD 4 speed and mounted up with no modifications to the cross member. The distance from the face of the tranny to the center line of the tranny mount was the same for both the 3 speed and 4 speed and the distance down from the centerline of the output shaft to the face of the tranny mount were the same. I read that early B-bodies did have tranny mounts in a different location. Later, all trannies used the tranny mounts in the same position.
3. The z-bar pivot on the 3 speed bell housing transferred directly to the 4 speed bell housing. The truck pivot was longer and in a different position but its mounting pad is in the same location.
4. I had to use the truck clutch fork because its pivot in the bell housing was a ball on the truck and a bracket in the 3 speed and they were not interchangeable (bracket bolts on with two screws; the ball pivot is a single thread-in post). The extra 1" length on the truck clutch fork does not interfere or cause any problems. I am running 6 into 2 headers with this setup.
5. The front boss on the front shifter pad on the OD 4 speed interferes with the A-body torsion bar cross member. You can either dent the cross member or do as I did and cut the boss off the trans. tail housing.
6. The output shaft on the 3 speed is smaller than the 4 speed. You will need a slip yoke from either a 4 speed or 727 car with a universal joint size that matches your drive shaft (or get a crossover "problem solver" universal joint).
7. I forget the actual dimension but I had to shorten the drive shaft about 3 3/8". (Measure everything once the setup is in the vehicle and resting on the ground at ride height.)
8. I used standard 4 speed A-Body shifter rods. The flipped over 3/4 lever puts the rod close to the cross member but since I was fabricating a mounting plate anyway I made sure that I had enough clearance before drilling the shifter mounting holes in the new plate. I used the standard A-Body shift mounting plate (adapter) along with about 1/2" of spacers on my fabricated mounting plate to locate the shifter towards the left so it came through the floor in the correct position, closer to the driver.
9. The shifter mechanism that was on the truck was made by Hurst and looked just like a Competition Plus shifter without the adjustable stops and had the bayonet attachment for the shifter handle. I used this shifter with a handle off an old 3 speed shifter. I did have to ream out one hole on the shifter and one of the tranny levers to get the A-Body linkage rods to fit.
10. The speedo drive mechanism and gear from the 3 speed swapped directly into the OD 4 speed so calibrating the speedo for the tire diameter was not an issue.
Dave Clement
