The Dodge Diplomat / Plymouth Gran Fury
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The 1980s saw the M-bodies (Dodge Diplomat and Plymouth Gran Fury) in extensive use as pursuit and detective cars. Though the standard 318 could not hold a candle to the 440, it proved to be extremely durable, capable of taking much abuse, and sufficient for most cops. The optional (in some years) 360 was more powerful and better suited to pursuit use, but relatively few squad cars of any make were pursuits.
Most Diplomat 318 squads (keeping in mind that this includes municipal as well as state police vehicles; the latter are more likely to have pursuit options) seem to have been fitted with a standard two-barrel carburetors, as well as the usual electrical, suspension, and transmission upgrades, for use as detective cars and low-performance patrol duty. The four-barrel carburetor added some power but had about the same torque; Danny Moore reported that they had roller cams and 360 heads. The 1975 318 four-barrel produced about 165 hp and 240 lb-ft of torque, while the 360 two-barrel produced 180 hp and 290 lb-ft.
The Lean Burn system was common; some have recommended replacing it with a Mopar Performance electronic ignition system (with standard spark advance controls) due to its tendency to fail with age.
The E48 option was the 318 four-barrel; the E45, the 318 two-barrel; and the general squad package, A38. In 1984, they switched to a new scheme, and the squad package became AHB, and the two and four barrel 318s became, respectively, the ELD and ELE. The AHB package would, until the end, provide firm-feel power steering; extra heavy duty suspension with front and rear sway bars, heavy duty front and rear springs, strut bushing, and shock absorbers; and wide-ratio TorqueFlite automatic.
The heavy-duty A-727 automatic transmission appears to have been dropped in 1983, leaving the capable, for most uses, A-904 or A-999 in its place. Danny Moore wrote that the A-998 had four or five clutches while the A-904 had three; by 1975, the A-998 was used with the 360 two barrel, and by 1983 the A-727 was changed to the A-904 in squads. (Torqueflite details.)
The "economy" rear gear ratio of the later squads (2.24:1) may have reduced city gas mileage, acceleration, and top-end speeds, though the 2.94:1 ratio was available. The result was a V8 powered squad car (Gran Fury, 2-barrel 318) that had the same acceleration as the 2.2 liter Plymouth Reliant. Unfortunately, the Diplomat never saw the Magnum head, cam, manifold, and fuel injection treatment that would raise power from to 230 hp. By 1988, the standard 318’s gas mileage was rated by the EPA at a lowly 15 city, 19 highway.
The last year for the Diplomat and Gran Fury was 1989.
Another source wrote: (A) county in Florida took several 1988 and 1989 Diplomats and worked them over to become drug interdiction cars. The 318 was replaced by the new crate motor from Direct Connection. Rumored horsepower was a manageable 350 net (!) with about 425 foot pounds of torque. Top speed was in the neighborhood of 145 with these cars. Naturally the chassis and brakes were changed to protect the innocent. The units are still being used sparingly for special cases.
Curtis Redgap wrote that the last Mopar cruisers used by the FHP was the 1987 Diplomat, with the four-barrel 318. It is claimed that the factory dropped several hundred 360 engines into the FHP Dodges. These less than aerodynamic styled jobs had a 130 mile an hour top speed and could sprint to 60 from rest in 8 seconds.
Dennis O'Connor wrote: These cars were also used by New York county Sheriffs departments and I personally saw them in the eastern most counties near Connecticut (where I live). At the time, late 1980s and early 1990s, I was part of a drum and bugle corps that marched all over Putnam County NY and adjoining counties. The cruisers were very nice looking (white with green and tan markings) and VERY fast with great handling. I saw several on the 2 lane state roads that were their stomping ground (versus NY State Police on the Interstates) in full pursuit/response mode and they were unreal. Those were not 318s for sure and they cornered far better than my much improved Camaro from that time. Whenever I got to talk to a deputy about the cars they said they loved them and only smiled when asked details like engine size. Don't know if I can ever find out more but will keep you in mind if I do.
"WWBroach" wrote: I am not positive about this but it's a theory. Ford released the 4.6 in the Mustang in 1996, but our 1992 Crown Victorias had the 4.6 engines...our motor pool said Ford was using the police cars to test the durability of the new engine. It may be that the late 1980s mopars were 318s, but with Magnum heads doing the same testing. I thought about this because I have a friend with a Duster that he has put a basically stock 5.2 Magnum converted to a 4bbl in it and you would not believe the power this thing has for a production small block.
Danny Moore added: Remember the new gas tank shield they have started putting on the new Crown Vic police packages? Well, my Diplomat already has the shield between the rear axle and the gas tank, and it is 15 years old!
Problems
I was never convinced that a used squad made for a decent daily driver. The only way that I ever saw any success in that respect was a complete, detailed overhaul. Essentially, when the wrench work was done, the car was mechanically brand new.
Another terror to beware of in the "M" bodied Diplomat and Gran Fury was the suspension towers. All of a sudden you couldn't keep the babies in line, and got some real squirrely handling. It took Chrysler a while to figure this one out. However the shock towers of the front suspension sagged inward! LA and LA Sheriff banned the transverse torsion bar suspension from participation in the bidding process. This problem started showing up as early as 1980!
To make matters worse, the K-member of the frame where the suspension was mounted, cracked, allowing further degradation of the sagging due to low quality tensile strength steel. This was particularly evident in the 1984, 85, 86 and 87 "M" bodied cars.
Once the suspension exhibited the nasty habit of going out of alignment within hours of having been reset, the only cure was replacement of the K-member and the shock towers. A rather expensive fix.
As a sort of back handed tribute to Chrysler engineering, this "out of alignment" problem was related ONLY to severe service, i.e.: Police cars and or taxis. It was also directly proportional on the type of driving it had received. The NYC police, operating on the bombed out streets of the Bronx and Manhattan, had suspension problems within weeks. A Nevada Highway Patrol might never had exhibited any problem at all. No civilian vehicles were ever reported with this sort of problem. Chrysler did solve the situation by 1986, however, they won't discuss the cure, unless you happen to be a Police Agency with a suspension problem! They did NOT make the fix at the manufacturing end!!!! Not until 1988. WHY??? Obviously the tower mounts had to be replaced, and the K-frame as well.
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