Another GM Parts Book Leak Confirms Grand Sport Specific RPO Codes

With today being the final day of 2025, why not go out with some fireworks of our own making!

There has been a ton of Grand Sport rumors hitting the Corvette Nation recently, and we’ve got another direct from the GM Parts Book. Our friend JMB56 from the MidEngineCorvetteForum has been a great source of this recent news, and the dude abides once again! After learning that the RPO code for the upcoming Grand Sport engine could be designated the LS6, he found that code listed under the upcoming RPOs for the 2027 model year which described it as a 6.7-liter small block V8.

It’s rare to get a second bite of the apple with leak like this, but we sent him a note back asking to look for several Grand Sport related codes and he got a hit on all three!

We can’t understate how this important these two reveals have been, as they confirm both a Grand Sport model and a new engine called the LS6 are coming for the 2027 model year. That information is sourced from GM’s own parts system. We’re sure that they will remove these codes now that they’ve been outed, but other than searching for a mythical manual transmission which I don’t believe will ever happen during C8, this is most likely the last leak we’ll see from this source.

But let’s talk about these three codes and what they represent.

GM uses Regular Production Codes for describing various options or packages and all three of these have been associated with Grand Sport models across the modern generations starting with the 1996 model year where it was offered as the swan song for the C4 generation. The Grand Sport model was reintroduced as a C6 (2010-2013) and then again as a C7 model (2017-2019).

In 1996, the Z15 RPO Code was actually used for the other special edition offered during the model year called the Collectors Editions while the Z16 code was used for the 1,000 Admiral Blue Grand Sports with the one-year-only LT4 V8 engine. However, for both the C6 and C7 generations, the Z15 RPO code was used exclusively as the Grand Sport Heritage Package, which included the fender hash marks and racing stripes, as well as some interior upgrades including badging and floormats. We believe the Z15 in this case carries on that tradition of packaging the car with Grand Sport specific graphics.

As for the Z16 package, it’s simply listed as an “Appearance Package, Special Edition” and it’s very possible that this could be a specific Grand Sport Special Edition model. In 2017, GM released both the Grand Sport Heritage Package and the Collector Edition package which was like having two “special edition” Grand Sport models. However, the Z25 code also implies a special “limited edition” anniversary appearance package as well. That’s really got us wondering as 2027 is not one of the official anniversary years. The 75th Anniversary will happen in 2028. It has been 10 years since the C7 Grand Sport was released in 2017, but other than that, we are stumped.

The Z25 Code was also used for the 2017 Grand Sport “Collector Edition,” and that same code also designated the 1993 Ruby Red 40th Anniversary Package, the 2003 50th Anniversary Package, and the 60th Anniversary Package in 2013.

These codes aren’t universally “Grand Sport-only” and it’s quite possible that Z16 and Z25 have nothing to do with the Grand Sport model or even the Corvette as we are unsure how the codes are organized. But all three of these codes have overlapped with Grand Sport models over the years, especially for appearance and Heritage elements, and so it makes sense that we would be seeing them again for the C8 generation

The first leak confirms the new LS6 6.7-liter V8 engine is in the works, and now we have confirmation directly from GM about a “Grand Sport” Heritage Package that will also be offered, as well as the possibility of two special edition packages. The 2027 Corvette is shaping up be one of the more interesting model years of the C8 generation which amazingly brought us the ZR1 and ZR1X just the year prior. It really is a great time to be a Corvette fan!

Editors Note
As our last post caught the attention of the major automotive websites, you have our permission to use both of the watermarked images showing the three RPO Codes and the LS6 designation, and we just ask for a link back to this article in return.

Source:
General Motors Parts Book

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