After long deliberation, three lawsuits, murder, world war(s), tea-leave consultations and a glance at some AMC TSMs (aka tea-leaves in a cup) I've determined with good certainty that the direction of the cupped washers on strut bushings is totally arbitrary. Sort of.
The TSMs I have do not spell out assembly in detail, but have grotty little pictures that "hint". Here's what I found. Schematic drawing of the strut with front-of-car on the left:
1963: ---------------------( |== (-- (one piece)
1970: ---------------------( |= =| )-- (two piece)
1972: (drawing vague) ---------------------) |= =| )-- (two piece)
1974: ---------------------( |== )-- (one piece) (see notes) ---------------------( |= =| )-- (two piece)
1977: ---------------------( |= =| )-- (two piece)
Pre-1965 don't really count, as they are of a different design than later parts, though the general design (load-bearing bushing and all that) is the same they use a different part.
I've used three different brands of rubber and one polyurethane part. All the rubber parts were of different shape.
_ The "traditional" one is a simple truncated cone with a cylindrical base, plus the stepped part that fits in the hole.
_ The most-recent part is the same, except the truncated cone is undercut; it has a concave shape, probably the cheap bastards saving a bit of materials cost.
_ The third shape is very substantial; the center steel bush instead has a flange, goes on the outside of the (included) cupped washer, which is nearly 1/4" thick, and the rubber is massive. Looks like a truck part! Might be a Jeep part.
_ The poly part was a copy of the traditional shape; I cut these down for the Rambler fix.
Alas, I did not record the brand names of these items, except that the most recent, undercut part is NAPA 274-9054. MOOG #K3090, Perfect Circle #FA685 are good-quality "traditional" ones, and Norris McQuay? FA685 might be the super-good one.
( ) The cupped washers.
|== is the old-style one-piece bushing. Parts stores always list it, but in my lifetime I have never seen one available, and yes, I asked. NOS parts for 1963-1964 are available; I bought one and it self-destructed within days (ancient rubber).
I find it strange that it's mentioned in 1974 (though it would be a different part than 1963-1964) and not in 72 or 77.
|= =| The two-piece bushing we all know and love and