To make sure everyone is on same train of thought, the end link bushings (green box) are ones close to wheel. The frame bushings generally attach to frame (or K-frame), but our design has a link between the bar and frame (orange box).
There is a total of 10 front sway bar bushings (2 end links (purple lines), 2 link to K-frame (blue lines) and 1 center sway bar (red arrow), per side).
The front end-link bushings are all the same.
The center link to frame bushings are all the same (but different from end link bushings, if I recall correctly).
The sway bar (center) bushings come in different diameters (small, medium and large) – based off the three-different sized front sway bars – Normal, heavy duty and police (police are also referred as Extra Duty). I do not recall seeing a factory heavy-duty bar (HD), before (that I recall).
The regular bars are about 1” inch in diameter (25.4mm).
The police/ED bar is 1-1/8” in diameter (28.6mm).
Again, I have no idea on what the HD bar diameter is (don’t recall ever seeing one).
Aftermarket has come out with different bar diameters – so that might be part of the difference.
The bar bushings are different shaped than most replacement bar bushings are – so if possible take a (old) bushing with you, before buying (to match up).
The center links are the weak link (behind the rubber bushings wearing out) of the front sway bar. I have replaced a bunch of those links before (I doubt the owner even knows they are broken. The police/ED version are a tad bit stronger – but not strong enough.
The center links from Firm Feel are a huge upgrade – but as far as I know, are only available as part of their front sway bar kit.
http://www.firmfeel.com/fmj_body_mopar_front_sway_bar.html
Matter of fact, anytime I’m at a pull-a-part and find an FMJ (or newer B, C or R-body), I try to grab any good links. Here lately, almost all the cars I have found, at least one link is broken. Currently I have 2 spares – but holding onto them until I can obtain the Firm Feel bar kits (at $400 each (US), times 4, in my case), in case I have another one break on me.
If I recall correctly, the rear police sway bar is ¾” diameter.
Note: I do highly recommend replacing any rubber sway bar bushing with urethane - for any car, not just for an FMJ vehicle (unless you are restoring one back to factory specs).
They cost a bit more but are well worth the price difference. Urethane sway bar bushings will not add any harshness to your ride and makes the sway bar work harder (the sway bar comes into effect a lot faster, sense normally you are waiting for rubber to compresses, first).
If I have any say in the matter, I will not install any rubber sway bar bushings.
BudW
Edit: the police/ED center links are made differently from the normal/HD versions. Also, the outer diameter of the bar bushing is smaller for police/ED bars. So not only is the inner diameter different but outer diameter is also different – which is why I recommend taking an existing bushing with you to parts store – to match up with.