Will a 1997 4L80e be compatible with my 91 7.4 454

[XxTinmanxX]

Hello, I’ve been trying figure out what transmissions I can use to replace my existing. At the moment I’m looking at a 97 4L80e and wondering it will work. But any suggestions or recommendations for a 91 7.4 would be appreciated. Also considering rebuilding it, how hard is it? Does it require a transmission magician? Lol
Thank you!!

 

[ak diesel driver]

No it will not. Rebuild it or have it rebuilt but you need to make sure if someone else is rebuilding it that you get your transmission back. We've heard WAY too many stories of tranny shops swapping transmissions and then it not working.

 

[Will L.]

The 4l80e has minor changes year by year. DEFINITELY have yours rebuilt.

 

[XxTinmanxX]

No it will not. Rebuild it or have it rebuilt but you need to make sure if someone else is rebuilding it that you get your transmission back. We've heard WAY too many stories of tranny shops swapping transmissions and then it not working.

Alrighty, that’s what I’ll likely do. Dang that’s wild and unfortunate. Thanks for the info tho!

 

[XxTinmanxX]

The 4l80e has minor changes year by year. DEFINITELY have yours rebuilt.

Roger that compadre

 

[dbrannon79]

Welcome to the forum @XxTinmanxX

Same answer from me too! NOPE! there are parts in your 91 trans that are NLA even for shops that rebuild them. things like the reluctor ring. don't let that scare you though, 99% of the time all of the NLA parts are reused during the rebuild process. iirc 91-93 are compatible, but you must use the correct torque converter for your engine. 454 used the same TC as our beloved diesels, they are a low RPM TC. other gassers like the 305 or 350 use a higher stall TC and won't work.

search around here and find post in other threads from @THEFERMANATOR He is the expert on these transmissions and has split loads of solid info about them.

the only way a 97 model 4l80e will work in your 91 is to ditch the factory PCM, remove any and all TBI injection, install intake and carburetor. Then spend $$$ on an aftermarket trans controller like EZ-TCI or others. that cost alone will exceed the price of having yours rebuilt!

It's all about your budget and your use case for your truck. if $$ is not an option, I vote on ditching the OEM PCM, swap in the newer trans. then go after a Holley Terminator for the trans and engine with multi port fuel injection. make you one heck of a work horse or something you can take to the track or off-road!

We all can help you on your journey which ever route you decide. But if your like most if us here, money is a BIG limiting factor, keep your eyes pealed on market place and other bone yards for a 91-93 donor parts truck with a good drive train. do the swap and hold on to the old one for one day you might get to rebuild it your self. once you acquire / fabricate the special tools needed, it's not that hard to do. lots of good videos on the institute of youtube out there plus us here to help wrench on your truck from afar.

P.S. we all can help spend your money too HAHA!