In 1967, Chrysler Corporation changed the "muscle car" business forever by offering some of the fastest production cars ever unleashed on American streets, the Plymouth GTX and Dodge R/T models. The GTX was based on the Belvedere, while the R/T was based on the Dodge Coronet. There was no Charger R/T for 1967, although the 440 Magnum engine was optional.
"Lesser" models offered beginning in 1968 were the Dodge Cornet Super Bee and Plymouth Road Runner. These had the 335 HP 383 V8 standard with the 426 Hemi optional. Later, in mid 1969, the 440 "six pack" package was optional.
The GTX and R/T featured the 440 cubic inch wedge V8 developing 375 horsepower as standard equipment, with the 426 Hemi as optional equipment. The badly detuned "Street Hemi" did not live up to its reputation on the street; the 440 Magnum (Dodge name, called Super Commando in Plymouths) would beat it in the 1/4 mile consistently. Considering the fact that it cost approximately $1100.00 as an option on a $2700.00 car, the Hemi wasn't worth the money in the day.
Today, the Street Hemi is highly prized as a collector item because of the fact that so few were ordered. (word traveled fast) Chrysler only offered it to make the engine legal for Nascar, where it really performed. Unfortunately, the engine offered to the public bore no resemblance to the Nascar engine. My best friend had a brand new Hemi Satellite in 1966, and it was a complete pig. Unless you replaced the cam and installed a better rear axle ratio, it just wouldn't move.
The 440 six pack was the engine to have....introduced in 1969, it was rated at a conservative 390 horsepower. It had higher compression, a hotter cam, and some different internal components than the 440 Magnum. It featured 3 Holley two barrel carburetors on an Edelbrock aluminum manifold (1970 and later models had a cast iron Chrysler manifold) rather than the 440 Magnum's single 4 barrel. With a little tuning, the six pack would beat anything on the street. Six pack (Dodge name, Plymouth called it 440 6 barrel or 440-6) cars for 1969 had a 4.10 Dana rear, lift off hingeless hood, 15" steel black rims, and chrome lug nuts. Air conditioning and disc brakes were not available. The cars also had no wheel covers. Drag Racer Ronnie Sox turned 12.9 @ 111 mph in the quarter mile with a showroom stock 6 pack Road Runner.
For 1969, the Six Pack was optional ONLY on Road Runners and Super Bees. It was not available on the GTX or any other model, but would be greatly expanded to most models in 1970. GTXs and R/Ts built prior to 1970 that have this engine are not original, although they are still very desirable drivers.
Today, these cars bring good money. Before purchasing one, check the current auction prices. Fully restored cars (properly done) bring big money because restoration costs are horrendous. Clones are worthless in the collector car world....sorry, that's just the way it is. No respectable collector like Jay Leno or Reggie Jackson will touch one.
"Numbers Matching" is what you want...... that means that the car's serial number, engine stamping, body tag, and transmission casting number are all as installed by the factory. A 1967 GTX with a 1975 440 engine may look good, but it isn't authentic. Again, always be sure that the car has the critical components and trim pieces intact. "Project cars" are junkers that require huge amounts of money to restore and are often not worth it. MoPars can be verified by Galen Govier, a real expert in this field.
The GTX and R/Ts are awesome cars to drive, and are some of the best mucle cars ever built. My friends owned them, and so did I. They are dangerous in the hands of the wrong person, they are just that fast. I was almost killed in a 1968 Charger R/T when we crashed into two other cars at almost 150 mph. Yes, they would go that fast with no problem. Today, they sit in heated garages as monuments to an era lost forever. What a shame.