6l90e keep or swap?

[rustyrodknocker]

Hello ls swappers. I'm getting ready to swap an 08 6 liter and 6l90e inty o my 66 suburban. The donor truck has no reverse. I have learned that this is very common with this era of trans. Likely a failed clutch shell.
Something I'm struggling with is the cost of rebuilding is nuts.
Used units are likely to have the same issue. Also all sources I've reached out to have recommended swapping in the old internal ecu to avoid communication issues. With any option likely needing dealer programming.

So this bears the question. Am I better off to swap to a 4l80e? Or does the wiring harness work that comes with that option equal the brain damage associated with the 6l90e?

I will appreciate any feedback. I've been stuck on this for months. It is an issue that money will clearly fix. But the cost is just more than I can justify, to put a used motor in an old truck. I recieved an estimate today for all parts required to convert one of my big block mopars from auto to built t56 and its less money than rebuilding a chevy transmission!

[pcmcobra]

I have been struggling through similar...Pretty much decided to stick with 6l90e
you can get a reman with 18mo warranty. for 2500+ core
locals want 3600 for stock rebuild, probably the minimum of parts.
I thought about going 4l80e, if you stay with gm ecm, you need something other than e38 ecm and trans control, or just go holley. The price point on either way is almost the same.
Deciding has driven me nuts for months. the 6l90's are pretty tough. That's from experience, and not reading intarwebs.

[prodjay10]

Try fix it yourself. Look for a transmission parts supplier in your area. There is a bunch of info online on trannys.

[rustyrodknocker]

When I bought the donor I thought it was a 4l80. I was not aware of the 6l90. The complete parts kits are available on line with clutch shells included for $650 ish. I had originally figured that plus a half day out half day in and a day on the bench. At $100 an hour that's $2250. if another half day is needed for programming I'm ballparking $2650. But most estimates have been twice that or more. I bought the truck from the company I work for because they got a quote of $7500. The truck is not worth that so they sold it.
I contacted a seller out of Missouri but I let out what I was doing and they declined to sell to me. They require a vin number to verify the application. Which I have, but once they knew of the swapped they said they could not sell to me. I suspect that alott of the privateer tranny shops are just using rebuild suppliers and doing swaps and that is their core customer base.
All the shops That I contacted also added that there could be a chance that final coding may have to be done by a dealer, which could add $500 after the fact.

This is a long way from the old th350. I can't believe how the selling point on so many 8 year old cars is "new transmission!". Huh? Why?
The old torqueflight has never been out of my 69 chrysler. Its a little soft but I take it anywhere.

[prodjay10]

They wouldn’t sell you parts for that transmission because you said you were swapping it into an older vehicle?

[OutlawDrifter]

Originally Posted by rustyrodknocker

I recieved an estimate today for all parts required to convert one of my big block mopars from auto to built t56 and its less money than rebuilding a chevy transmission!

Either your search swath is limited or you're not talking to the right people.

If you can put a T56 behind a MOPAR(including trans) for less than a rebuild, something is wrong. Or you just scored the deal of the century.

The 6L90E is an awesome trans, I had one in a 2500HD. I've got a 4L80E in my '49 GMC behind an LQ4, some days I wish it had the 3.06 1st gear of the 4L60E, but I know I'll never have to worry about destroying it with sub 400whp, 3600lbs, and traction.

[dayj1]

Originally Posted by rustyrodknocker

When I bought the donor I thought it was a 4l80. I was not aware of the 6l90. The complete parts kits are available on line with clutch shells included for $650 ish. I had originally figured that plus a half day out half day in and a day on the bench. At $100 an hour that's $2250. if another half day is needed for programming I'm ballparking $2650. But most estimates have been twice that or more. I bought the truck from the company I work for because they got a quote of $7500. The truck is not worth that so they sold it.
I contacted a seller out of Missouri but I let out what I was doing and they declined to sell to me. They require a vin number to verify the application. Which I have, but once they knew of the swapped they said they could not sell to me. I suspect that alott of the privateer tranny shops are just using rebuild suppliers and doing swaps and that is their core customer base.
All the shops That I contacted also added that there could be a chance that final coding may have to be done by a dealer, which could add $500 after the fact.

This is a long way from the old th350. I can't believe how the selling point on so many 8 year old cars is "new transmission!". Huh? Why?
The old torqueflight has never been out of my 69 chrysler. Its a little soft but I take it anywhere.

The $7500 price caught me way off guard. That just seemed way, way, way high.

Anyway, you can get a GM rebuild for $1200. I know you'll have to ship it and return a core, but it's still way better than $7500. I didn't do any price comparisons. It was just the first hit I got for the part number (which is 17804007 by the way)

https://paceperformance.com/i-713409...nsmission.html

Edit: On further review, I see that part 17804007 is superseded by 19303196. Pace, in particular, must be trying to get rid of some "old stock" as the new part number is more like $3K (and they only show as having 7 units left). Either way, maybe the $1200 GM rebuild is something that will help you out.

[Daaaanz67]

Interesting, had a friend give me a 2016 6l80 out of a wrecked school van with 56k. I’m wondering if it’s worth using also? Not trying to hyjack this thread but pretty much same trans?

[prodjay10]

If you need parts, there are a couple places in Phoenix I could put you in contact with. They’ll sell you what you need.

[LS short box]

Just FYI. I saw your post and just looked at MN Craig's list under auto parts. There is a trans shop in St.Paul MN that lists rebuilt 6L90E's for $1200. I don't know them or any details just thought you might want to give them a call and see what they can do for you. If its what you need at price some what close to the $1200 listed even if you had spend $300 on shipping it might be interesting. Also don't know what they charge for a core charge.

[Killer Bee]

just a little food for thought from a mechanic's perspective..

after comparing repair costs of the 6l90 you have with complete donor accoutrents vs a 4l80 replacement purchase and install mod costs, you may find that difference negligible to the overall project expense.. and the engine and trans mated pair you have may also prove easier and less expensive to work with now and down the road.. so you really have to ask yourself, if you're going that far anyway, will you regret the swap and be satisfied in the end with the difference?

good luck on a tough decision!

[rustyrodknocker]

Originally Posted by prodjay10

They wouldn’t sell you parts for that transmission because you said you were swapping it into an older vehicle?

Not sure what turned them off. I had originally planned on getting the trans working correctly in the donor before swapping over. As mentioned I think they are a large volume rebuilder that sells to transmission shops for swap outs. But they are not willing to sell to me.

[rustyrodknocker]

Originally Posted by OutlawDrifter

Either your search swath is limited or you're not talking to the right people.

If you can put a T56 behind a MOPAR(including trans) for less than a rebuild, something is wrong. Or you just scored the deal of the century.

The 6L90E is an awesome trans, I had one in a 2500HD. I've got a 4L80E in my '49 GMC behind an LQ4, some days I wish it had the 3.06 1st gear of the 4L60E, but I know I'll never have to worry about destroying it with sub 400whp, 3600lbs, and traction.

Yea kind of my point of reaching out to people here. Ive called several transmission shops and contacted online sellers. $4500 was the lowest number, with a caveat of a $500+ trip to dealer may be required.

[rustyrodknocker]

Originally Posted by LS short box

Just FYI. I saw your post and just looked at MN Craig's list under auto parts. There is a trans shop in St.Paul MN that lists rebuilt 6L90E's for $1200. I don't know them or any details just thought you might want to give them a call and see what they can do for you. If its what you need at price some what close to the $1200 listed even if you had spend $300 on shipping it might be interesting. Also don't know what they charge for a core charge.

I will check that out. Thank you.

[rustyrodknocker]

Originally Posted by dayj1

The $7500 price caught me way off guard. That just seemed way, way, way high.

Anyway, you can get a GM rebuild for $1200. I know you'll have to ship it and return a core, but it's still way better than $7500. I didn't do any price comparisons. It was just the first hit I got for the part number (which is 17804007 by the way)

https://paceperformance.com/i-713409...nsmission.html

Edit: On further review, I see that part 17804007 is superseded by 19303196. Pace, in particular, must be trying to get rid of some "old stock" as the new part number is more like $3K (and they only show as having 7 units left). Either way, maybe the $1200 GM rebuild is something that will help you out.

Im going call these guys. Thank you. Looks like a $1000 core charge but free shipping potentially. They say to call for availability.