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Corvette C3 Luggage Racks

C3 Corvette C3 Corvette
Luggage racks on C3 Corvettes have been controversial for some time.  Enthusiasts either love them or hate them for different reasons.  Personally I like them and I feel the rear deck looks kind of blank without them.  The racks were always available from GM and were a dealer installed option until 1977 when they could be ordered as a factory option code V54.  V54 included the chrome rack and adapters for carrying the roof panels.  Cars coming from the factory with the V54 option did not include the bags for storing the roof panels and did not include the storage straps in the cargo compartment for anchoring the panels down.  The assumption by GM was that the roof panels would be stored on the luggage rack when not in use.
Original GM racks were chrome plated.  The 1977 racks had pins installed on four of the rails for securing the top adapters.  Luggage racks are now available in both chrome and stainless.  The pre 1977 racks were retained to the deck with six bolts while the newer 1977 racks were retained with eight bolts.  All racks were retained by rubber well nuts.  This mounting system allowed the rack to be installed completely from the top deck. 
The bolt patterns of the racks differed from one manufacturer to another.  If you have a six bolt rack and wish to change it to an eight bolt rack don't expect the six existing holes to line up with your new rack.  Before you replace a luggage rack make sure you measure all hole dimensions so that you can compare them to the rack the potential vendor may be selling. 
The eight bolt chrome racks are designed to accept the roof storage adapters.  The adapters can be fitted to the six bolt racks by drilling the rails and adding the retaining pins at the appropriate locations.  Some vendors offer the pin kits.  They can also be added to the stainless racks as well. (See diagram at bottom of page for proper positioning of pins)
With the rear deck design change to accommodate the larger glass window in 1978 the luggage rack option was no longer available.  In 1980 GM designed a completely different style rack for carrying the roof panels.  About 10% of Corvette production between 1980 and 1982 left the factory with the new V54 option. 
Below are the most common rack dimensions but there are some manufacturers whose racks will differ.  If you just adding a new rack and the holes are non-existent then you do not have to worry but if you are replacing a rack, the dimensions are important.
C3 Corvette
C3 Corvette
6 Hole Chrome
8 Hole Chrome
C3 Corvette
C3 Corvette
6 Hole Stainless
8 Hole Stainless
C3 Corvette
C3 Corvette
C3 Corvette
GM Installation Guide for V54 Roof Panel Adapters on the Luggage Rack and Pin Positioning Dimensions
C3 Corvette
This is the Roof Panel Adapter Kit that came as part of the V54 Luggage Rack Option.  These kits are available from many Corvette C3 Part Vendors
A word about the well nuts, because they cause more trouble than the rack itself. A well nut is a rubber sleeve with a threaded insert, and it does two jobs at once: it grips the deck and it seals the hole against water. The rubber hardens with age, and once it does it stops sealing and stops gripping. If you are pulling a rack off a car that has not had one off in thirty years, plan on replacing every one of them. They are inexpensive, and they are the only thing standing between the weather and the inside of your rear deck.
Go easy tightening them. You are threading into rubber that is sitting in fiberglass, not into steel, and there is no satisfying stop at the end. Snug is far enough. If you keep pulling on the wrench you will spin the insert inside the rubber, and then the only way out is to cut the old nut apart and start over. Worse, you can crack the deck around the hole, and that is a body shop repair on a panel everybody looks at.
Remember what the rack was designed to carry. GM put it there for the roof panels and a soft bag or two, not for a load of luggage. The deck under it is fiberglass and the load is spread over six or eight rubber nuts, so keep it light and keep it strapped down. Anything that can slide will find the paint sooner or later.
Chrome or stainless is worth a thought before you buy. If you are chasing originality then chrome is what left the factory and chrome is what a judge expects to see. Stainless will not pit or lift the way aged chrome does, and on a car that lives outdoors or sees winter salt it will still look right in ten years. I have seen plenty of good original chrome racks ruined by nothing more than being left wet.
One last thing for anyone thinking of taking a rack off for good. Those six or eight holes do not disappear when the rack does. Filling them properly and blending the paint across a rear deck is real bodywork, and matching an original finish is not a driveway job. It is worth deciding whether you truly dislike the rack before you start, because putting it back on is a great deal easier than taking it off for ever.