[Daves55Sedan]

I thought I'd seen this posting before until I scrolled down and noticed I made a couple of replies over a year ago. But reading back over Gerry Dubois statement, he would have been more accurate to say:
"The mechanical-advance distributor is essentially the same from the bowl up on all modern Ford units", instead of load-o-matic. And if it had been me, I wouldn't have used the term "essentially the same". Any minor differences that he knows of that would effect swapping internal components from one year distributor housing to the next should have been listed, so that the reader would be informed more of what he might not be able to do.
Here is what I would point out to the reader that might be valuable to him:
If you are still using an old load-o-matic dizzy and it works fine in your engine with your original carb, why change it? I had a Y-block with mechanical advance and didn't recognize ANY notable improvement in performance or gas mileage over a '55 load-o-matic. The only reason I would ever change is if replacement parts such as ignition points, condensers or vacuum advance cans were no longer available for load-o-matics. And folks were are essentially at that point now. '56 & earlier vac cans are no longer available for the V8, but still available for 6-cyls (probably because they were still using the 1952 vac can from the 215's in 1968 for the 240).
Also, Chinese made condensers are a crap shoot. Best bet is to keep what you have until it fails and carry a new one (or one from a junkyard dizzy) in the glovebox if your old one does fail. Has anybody seen the new load-o-matic ignition points that just came out in the last few years? They are disgusting. The point contact on the pivot arm is about 1/32 of an inch deep, but the stationary contact is twice as deep as the original design. In attempt to install the adjusting screw thru the point base, your screwdriver is hindered by the contact arm even with the points closed. It is terrible, as if they weren't hard enough to install in the first place. I'm still running mine with old parts, but if my vac can fails, I will be out of business.
I don't recommend pertronix conversions. They are woefully lacking in quality and can't endure even 160 degree heat from the engine. They're too expensive for such a short lifespan and I don't recommend taking a long trip using pertronix unless you are prepared to swap it back out for your old points and condenser on the road somewhere. Sorry, not me.
Folks with '57 and later engines or older engines converted to mechanical advance can easily select the year distributor they want based upon the type carb they are using. Easiest thing to do is to get the OEM distributor of the year that type of carb was used.
Beware of some of the dizzy rebuilding outfits. I have heard complaints of Cardone installing the dizzy shaft of the wrong length on Y-block dizzy's. In my town, there is a guy who is experienced in replacing bushings, bearings and shafts in starters, generators and dizzy's. If you can find a trustworthy local guy like that, it's your best bet.
Keep a good set of dizzy cap hold down clamps on your dizzy. Old ones tend to stretch over the years and allow the dizzy cap to shuffle around a little bit such that the rotor inside will cut grooves into the plug towers underneath. This causes the spark to jump a little gap between rotor tip and tower. if you are a cheap SOB like me, you can re-bend the curve on the clamps and place them in a vice. Heat them up red hot and take them out and drop them in a little metal tuna can full of oil until cooled. Then re-install.
Always try to get a cap with copper tower sockets and use a Q-Tip coated in silicone hi-dielectric grease to smear all inside the tower sockets regardless of the tower sockets being aluminum or copper. This will vastly help to preserve the tower sockets and plug wire terminals and keep green corrosion off of them.