This is the convoluted "rubber" boot on the end(s) of the steering rack housing that must retain the gear oil inside the rack as the steering and suspension parts move. The current problem (March 2013) is that the grooves around the ends of the boot are too narrow to accept the proper clamps. The apparent solution is to use nylon tie-wraps to secure the boots on the steering rack. The tie-wraps must be quite tight to prevent oil leakage.

The metal band clamps supplied may also be non-original. These may or may not fit original style boots with the wider end grooves, but they certainly do not fit these narrow groove boots.

Original rack boots had wider grooves to accept the metal band clamps. Boot material was synthetic rubber (Neoprene) and was fairly thick and durable. Original band clamps were similar to the one shown on left in the picture. The square nut was a little thicker; the bent over tab securing the square nut was originally a 90 degree bend; the original machine screw was Phillips slot round head (most likely), or possibly slotted pan head. Original clamps were same width but different diameter for opposite ends of the boot.

There have been various problems with these rubber seals in recent years. They have on occasion been made from inferior type rubber material, sometimes thinner than original, that would deteriorate while in storage or within a year before a restored car might ever see the road. Current material may be some kind of soft plastic, which may or may not be superior to the original synthetic rubber. For prior parts which did have the correct width for the clamp grooves, the material at the ends may be too thick so the original and correct clamp cannot be installed. Some prior supply replacement clamps may be slightly larger or slightly smaller than original, presumably to match some non-standard boot. It has been common for clamps not to match boots supplied on the same delivery order. Check these parts immediately upon receipt, and contact the vendor immediately if you have any such issues.

These parts have changed so often that the vendors have a problem keeping up with matching parts, especially with non-matching clamps. The most resounding issue is that the vendors very often use the original part number for non-standard parts that will not fit as original. When a part (like the one pictured above) will not exactly fit the application, it should be assigned a different part number and should be labeled "replacement type". When non-standard clamps are supplied that will fit the replacement type boot, those clamps should also be assigned a different part number and should be labeled "replacement type". The vendors then need to keep track of which clamps will fit which boots and publish the catalogs accordingly. If this had been done in recent years we would by now have multiple part numbers for boots and clamps. Since these parts are all commonly listed under the original part numbers, the only way you can know if the parts will work together is to compare all replacement parts, measure carefully, and/or try them on the car. There is likely to be no other solution to this for many years to come. Let the buyer beware.

Addendum 4/22/15:
One correct 11-rib rack seal has been found. Supplier is in Australia. See article Steering - SR-114B.