700R LS swap
Thread Starter
1st Gear
Joined: Nov 2025
Posts: 1
Likes: 0
700R LS swap
I have the chance to acquire a very clean 84, but I’m not sure that I want to stick with the crossfire. I’ve been doing some digging on LS swaps for the early years, and it doesn’t seem that bad. However I was curious on how well the 700R would work with a swap. I don’t plan on pushing crazy power (mid 300s is most likely) and keeping the auto in it would make the swap a million times easier. If anyone who has done something like this could weigh in, it would be appreciated!
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
I LS swapped my 84 years ago. I wouldn't mess with the 700r4. Mostly because to LS swap it right the 700r4 would NEED a new converter. The factory 700r stall speed is way too low for an LS. It would be much cheaper to by a low mileage salvage yard 2wd 4L60e with a stock converter. Then you can sell off your 700r4 and make a lot of your money back. You would need to fabricate a C beam adapter or buy a 6 to 4 bolt tail housing adapter. The factory driveshaft will fit just fine.
The other option is a 4L80e swap. This is what I have now. A bit more expensive but gives you lots of room down the road for more power.
The other option is a 4L80e swap. This is what I have now. A bit more expensive but gives you lots of room down the road for more power.
Burning Brakes
Joined: Sep 2017
Posts: 938
Likes: 168
I have the chance to acquire a very clean 84, but I’m not sure that I want to stick with the crossfire. I’ve been doing some digging on LS swaps for the early years, and it doesn’t seem that bad. However I was curious on how well the 700R would work with a swap. I don’t plan on pushing crazy power (mid 300s is most likely) and keeping the auto in it would make the swap a million times easier. If anyone who has done something like this could weigh in, it would be appreciated!
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
I agree, but it is a harder swap. I prefer the gear ratio of the 80e over the 60e. But if the super steep 1st gear doesn't bother you the 60e will work great as a super cheap option for a stock LS. That and the 80e requires a new driveshaft and a fabricated c beam adapter. For the 60e you need the $300 tail housing adapter and you can use the 700r4 tail housing with the factory C beam. Also the factory 80e converter is ridiculously heavy. You can get a billet 9.5" converter that's light and a good stall but that's another added cost.
Burning Brakes
Joined: Apr 2014
Posts: 829
Likes: 192
If you can find a donor vehicle with an LS and 4l80e grab engine, trans complete harness, pcm etc…. This way you get all the electronic management designed for that setup. If you get an entire vehicle you may be able to sell off the unused parts and get some money back.
We bought a 94 Z28 and used the engine and trans plus all electronics to swap into a 79 Malibu wagon. We paid $1000 for the Z28, used what we needed and sold off almost everything else for $1300. So, we actually made a $300 profit.
We bought a 94 Z28 and used the engine and trans plus all electronics to swap into a 79 Malibu wagon. We paid $1000 for the Z28, used what we needed and sold off almost everything else for $1300. So, we actually made a $300 profit.
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
If you can find a donor vehicle with an LS and 4l80e grab engine, trans complete harness, pcm etc…. This way you get all the electronic management designed for that setup. If you get an entire vehicle you may be able to sell off the unused parts and get some money back.
We bought a 94 Z28 and used the engine and trans plus all electronics to swap into a 79 Malibu wagon. We paid $1000 for the Z28, used what we needed and sold off almost everything else for $1300. So, we actually made a $300 profit.
We bought a 94 Z28 and used the engine and trans plus all electronics to swap into a 79 Malibu wagon. We paid $1000 for the Z28, used what we needed and sold off almost everything else for $1300. So, we actually made a $300 profit.
I disagree about the harness though. I've never had good luck with old harnesses. You can get a brand new stand alone harness that's made for whatever trans and LS setup you have for around $100. They even come with a small fuse box.
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Burning Brakes
Joined: Sep 2017
Posts: 938
Likes: 168
I have the chance to acquire a very clean 84, but I’m not sure that I want to stick with the crossfire. I’ve been doing some digging on LS swaps for the early years, and it doesn’t seem that bad. However I was curious on how well the 700R would work with a swap. I don’t plan on pushing crazy power (mid 300s is most likely) and keeping the auto in it would make the swap a million times easier. If anyone who has done something like this could weigh in, it would be appreciated!
Burning Brakes
Joined: Apr 2014
Posts: 829
Likes: 192
I actually dissected the Z28 harness and only used what was absolutely needed. In that process everything was checked and verified as good. I still have a big bin full of all the other unused wiring and related stuff. Ive used that a a stock for wiring for multiple smaller projects since then.