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So after new solenoids @ 199k miles and a new set of accumulator springs @ 255k; blossom ( my 01 SE, the star of the Lucerne radiator conversion) finally lost 4th @ interstate speed and slips intermittently from 4th at lower speeds... Yeah I know it's that *dang* clutch hub... But, I was originally planning on doing a 3.29 final drive swap, & thought to myself, why not swap a whole brand new transmission in with the 3.29 already in it. So hopefully some vets like jrs3800 could answer this: what all would be necessary for basically a non HD to a HD transmission? I've seen it's basically a drop in update save for there are some differences in the flex plate ( something about there being 2 different bolt patterns, & i already know the ECM is gonna need a update or swap to deal with it, not worried there, intense already has a file started on me.) Also saw ZZP has a " dual pattern" plate maybe just for this purpose. Anyways, thanx and hope y'all are running cooler with that radiator trick; i know with a 160 t-stat the highest she's gotten is 175 stuck in I-4 Rush hour with 104 degrees outside and the air conditioning running full blast

I have been through my 2003 ssei's transmission many times. You have a 4t65e transmission. The 4t65eHD is the same with the exception of having larger inputs for the CV axles and stronger internals(help me out experts if wrong). The HD version of the 65e is mated to cars with supercharged engines. The way you can get a lower ratio is by changing the drive/driven sprockets for the chain drive. Making the drive sprocket smaller and putting a larger driven sprocket would achieve the lower ratio.

I would also suggest a shift kit if you don't have one already installed along with an AFL valve and lighter forward band accumulator spring to prevent slide/Rev bang.

Not sure if the input shaft and stator support are the same, but am certain you can use your non HD converter. If going for a salvage yard transmission, check the pan...it tells a story. Hope my info was helpful and hope you find a good HD trans.

MOST IMPORTANT: make SURE the transmission you get has webbed bolt holes for the rear mount. If it doesn't, DO NOT get it. The webbed casting is there to support the stress of the engine's torque.

God bless, happy holidays.

The differences between the e and HD have been tossed back and forth for a couple decades. The real strength difference is the larger HD diff. IIRC 4t65-e transmissions have put into 12s in the mid-00s. The driver side axle will be the same but passenger will be shorter on HD equipped cars.

The FDR is the chain ratio multiplied by the diff ratio.
Chain drive gear teeth options: 35/35 37/33
Diff ratios: 2.86, 3.05, 3.29
Production FDRs: 2.86, 3.05, 2.93, 3.29

HD equipped cars have a larger 3.29 diff and 37/33 chain ratio. If you get an H-body 4t65-HD and swap the chain drive to 35/35 you'll have a 3.29 FDR 4t65-HD and the correct trans mount webbing/threads. There are some differences through the years. More info in that here:
https://www.3800pro.com/threads/4t65e-v ... ost-162433

Thanks for the assist 95naSTA

Team work makes the dream work.

Cheers.

So just order a fresh transmission and passenger side axel for an 03/04 ssei? And maybe a torque converter and plate to match?

The link I posted would suggest anything 03+ will not be directly compatible. From an SSEi, yes. I'm assuming you will swap the gears to 35/35 to get to a 3.29 FDR. I would probably get a n/a Pontiac GT or some other 3.29 equipped car converter since the stall speed will suit the FDR. You can use your stock flexplate this way also.

So...
01 ssei trans, passenger side c/v axle, & a fresh tune from intense and I cand get a transmission that should have the hardened shaft and 3.23 gears long story short? Just gotta stick with my year cause of the electrical setup? Those are the 2 main things I'm worried about. Cause by the time taxes get done and I get the money might need new bands, clutches, & god knows what else... And if I'm getting a new unti, I'd like to get something with the shortest gearing possible, helps with stop and go traffic and merging on I4

The one thing you're missing is you will have to swap the chain and gears in the SSEi trans to get a 3.29 FDR.

*dang*, so... Is there any way possible to get those 2 things in the same transmission without having to crack open the side pan? I'll be honest I don't even know if the ssei's got the 3.23, but being they got an "HD" I'm hoping that meant the hardened overdrive shaft went in them. And that's kinda the most important part to me ( don't wanna do this again even if i did get 270k) so; is there any possible factory units with the shaft and the 3.23's? & If not, anyone know of any outfits that would could make something special?

prof. utonium wrote:*dang*, so... Is there any way possible to get those 2 things in the same transmission without having to crack open the side pan? I'll be honest I don't even know if the ssei's got the 3.23, but being they got an "HD" I'm hoping that meant the hardened overdrive shaft went in them. And that's kinda the most important part to me ( don't wanna do this again even if i did get 270k) so; is there any possible factory units with the shaft and the 3.23's? & If not, anyone know of any outfits that would could make something special?

From 1997-2002, OD shafts were not hardened in the 4T65E (including the HD). Best thing I could recommend is call a dealership and ask what RPO codes represent the 3.29 FDR.

+++UPDATE+++
Found this. Looks to be VERY helpful

https://m.facebook.com/GM3800Tips/posts ... ale2=ar_AR

prof. utonium wrote:*dang*, so... Is there any way possible to get those 2 things in the same transmission without having to crack open the side pan? I'll be honest I don't even know if the ssei's got the 3.23, but being they got an "HD" I'm hoping that meant the hardened overdrive shaft went in them. And that's kinda the most important part to me ( don't wanna do this again even if i did get 270k) so; is there any possible factory units with the shaft and the 3.23's? & If not, anyone know of any outfits that would could make something special?

No factory 3.29 HD options in an H-Body specific case. (3.23 isn't an actual FDR)

Wow! Can we get some of those links stickied to the gear section? That's alot of good intel that kid composed on FB. Thanks for the info, did some research based on it and a few other sources and I'm starting to get an idea that could work... But *dang*; they kinda locked these things down so almost all you can do is a direct replacement is kinda the feeling I'm getting unless of course your willing to split cases and I was hoping i could get around it, which I may have found thanks to those links you threw me.

I have a spare transmission I went through that’s out of a 2004 GTP. I also have a spare 4T65E-HD for a 2003 SSEi. Unfortunately the GTP trans doesn’t have the webs cast for the rear mount as the SSEi trans does, and I don’t have access to it presently. Sure shifted good. Both have a Superior shift kit in it, AFL valve and lighter forward band spring. It’s the HD version.

You’d have to swap the valve body out too. Electronics changed in 2003 inside the trans.

Think this is gonna end with a phone call to triple edge performance... Although I did manage to confirm we can swap out same year w/body 4t65's you just gotta drill the bosses for the infamous rear H body trans mount. also seen some of them were packed with 3.33 & 3.60 gears, depending on specific application. Just gonna have to go big or go home on this one. thanks for all the Intel, we should seriously sticky those links to the gears section.

http://www.regalgs.org/topic/48473-all- ... our-4t65e/

Wow... 3.69 gears will definitely get the point across on the entrance ramps, think I'll end this by saying thanks for all the info, I'm gonna get ahold of triple edge & have something built to order dor this operation; it's kinda a go big or go home level; and i love this car and already have way too much put in to just ever give up.