I recently swapped a number of parts from a junkyard 86 Monte Carlo SS to my base model 85 El Camino with a TBI 4.3 V6. The main parts were high effort steering box, F41 suspension braces, 3.73 gear 7.62 rear end and the CX code 200 4r transmission.
The old transmission was a 200-C coupled to a 2.41 rear gear. I swapped the rear end out first. The swap didn't involve any modifications or fabrication. It swapped out bolt for bolt.
Going from a 2.41 ratio to a 3.73 with the original transmission was disappointing. I don't think the power band of the V6 matched up to the new ratio. My V6 has peak torque at 2000 rpm and peak horsepower at 3600 rpm. The seat of the pants feel was of the engine running out of breath very quickly! When I hit 55 mph the car labored to keep going. With the 2.41 ratio I would get the same effect at 80 mph.
The transmission swap was very straight forward. The only extra part I needed was a cross member from a 200 r4 G body car. The 200-C cross member connects to the transmission about 6 inches in from of the 200 r4. The 200-C cross member bolts on the drivers side to holes forward of the passenger side. The 200 4r bolts almost straight across.
The drive shaft, TV valve and the electrical connector were a straight swap on my 85. The transmission lines had to be bent using a tube bender. They were the wrong angle and without a bender would not have bent without collapsing. The 2.41 gear had a tan speedometer drive wheel. The speedometer cable length was just fine. When I swapped in a new blue gear, the speedometer read very accurately. The old blue gear in the 200 r4 was stripped. The column shifter was a straight swap. The D position is a smidge below D on the old indicator.
The CX servo transmission full throttle shift points are set for a L69 305 HO making peak horsepower at 4400 rpm. My V6 can't spin past 3600 rpm. Full throttle shifts are pointless until I change the engine or change the V6 camshaft. Part throttle shifts are firm, crisp and at a great rpm for the engine. The CE6F torque converter is a bit looser than the original.
With the trans-rear combo, the El Camino feels much more lively and fun to drive. Pickup is great and freeway cruising is effortless like before. The best compliment to this combo would be a L69 or L98 V8 or at least a B code V6 camshaft.
I kept the original coil springs. I added three frame braces. Engine cradle to lower radiator support. Upper radiator support to front fenders. An cross brace in front of the radiator. The SS rear end had a rear sway bar attached. All the braces were a straight bolt on. Together, it is unmistakable that the car feels more solid.
The last mod of this series was to swap the steering box to the high effort box. This was a straight swap as well.
I have about $500 in these swaps. The El Camino really feels like it went from grandpa truck to a SS performance vehicle.
