The silver anniversary of the LS6 has resurfaced rumors that a few aluminum-headed versions of the great engine found their way into the engine bays of SS454 Chevelles. However, taking into account records from GM's Tonnawanda engine plant, it seems very unlikely that such a beast ever showed up in a Chevy dealership. Here's why:

• According to the records of the Tonnawanda engine plant, no such aluminum headed LS6s were ever built.

• Though aluminum heads for the LS6 were considered for production by Chevrolet, records show the division canceled those plans on October 3, 1969. That was months before the LS6 production car was being manufactured.

• Though aluminum heads for the LS6 were considered for production by Chevrolet, records show the division canceled those plans on October 3, 1969. That was months before the LS6 production car was being manufactured.

• No such aluminum head option was listing in dealer order forms and no pricing information exists.

• Though suffix codes were issued for the proposed aluminum head engines, the engine didn't necessarily make it into production. The fact that some parts books and service manulas discuss such an engine isn't proof either. Manuals are often printed months before production actually begins.

• Even if some Chevy dealer did try and order such a car, Chevy would kick back the order if there was no engine, and the Tonnawanda plant never built such engines. All big-blocks were---and continues to be---built at Tonnawanda.

• The L89 aluminum-head 396 did have an ordering code and price information. According to Tonnawanda, they built 28 of those engines for '70 Chevelles; 18 for manual transmission duty, and 10 for automatics. Why wouldn't they have information for an L89-style LS6?

• The year 1970 was a strike year, and both the '70 Camaro and Corvette were delayed. It's common knowledge that the LS6 was scheduled for both of those cars, but never produced. Why couldn't the same thing happen with Chevelle?

• It seems funny that there was no mention of '70 LS6 aluminum head engine in 1970. Considering the extensive press coverage the LS6 at the time, it's almost inconceivable that such an exotic piece as the aluminum-head version would go unmentioned. Unless, of course, it didn't exist.