Hiya-

So, I am new to the forum and new to owning Bonnevilles. Not new to Northstars.
My car is an 05, spotless, cannot think of an option it doesn't have. 170k on the clock. And everything works. Drives like a new car. Save for the miss.

So, I am fixing it.

What I want to know is this- if I find an engine and transmission (may as well do them both) am I going to someday regret not having "numbers matching?"

And, in an effort to save time, will the engine cradle from an 05 sts interchange? Going to drive it as long as I can if numbers matching isn't an issue.

Thanks in advance!
Sean

WELCOME TO THE CLUB!!
why do you want to replace the engine?

_________________
poverty forces one to do unorthodox things

2000 SSEi
past rides:
1996 SSEi
1992 GTP
1987 Grand Am

Thank you- this seems like a great community

Lol. I guess that would help.

Head gasket. thw transmission is also shuddering at light throttle take off. I was looking at a 66 corvair when I bought this. Kind of feel like this will be the bigger project. I drive 100 miles a day. So the heated seats and HUD won the pros and cons list.

Probably worried about mileage.

Numbers matching is irrelevant anymore. An LD8, is an LD8, is an LD8. They aren't individually linked to the VIN#, vehicle, or product line anymore like the 60's. It's a GM Powetrain corporate powered engine in a GM corporate platformed vehicle.

As to the other question, a 2005 STS isn't a FWD vehicle like the Bonneville. It is on GM's Sigma RWD platform. Apples and Oranges... If you referring to a 2004 Seville STS, which does share the basic platform of the H-Body, I think there is enough variation to not be compatible. I don't think anyone here has ever done it, so I can't be 100% sure though.

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Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck

Wow- yeah, I was referring to the Seville. The folks owned a STS and I just assumed it was the same layout. They quit driving before it was out of warranty, so I never so much as checked the oil. It's funny, I have his Allante at the house now replacing switches and chasing down a short that drains the battery if it sits too long. If you ever want to hear a northstar through flowmasters, I can hook you up. SMH.

Anyway, that is too bad about the engine cradle. I read someone's post last night about needing to put back together immediately lest they forget where everything goes, that is partially why I was interested in if it would swap. I imagine there are a ton more sevilles in the wrecking yards than GXPs.

Again, there is a lot of confusion with GM platforms for the full size vehicles. Technically the Bonneville/88's/PA's are an "H" Platform and the Seville STS is a "K" Platform. However both are subordinates of the overall "G" platform that GM consolidated all into back in the late 90's if I recall. Of that "G" platform, the H is technically a larger version of it than the K, which leads me to believe it wouldn't work.

Again, this question, I can't recall, has ever been asked here because the situation has never arose.

_________________


Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck