swapping out 700R4 for 4L80e on LS 5.3 Gbody

[paradigm]

My car has a 5.3 LS based truck motor paired to a 700R4 that the prior owner swapped in. I am going to swap out the 700R4 for a 4L80e 2wd.

What parts should be replaced and sourced prior to the swap?

transmission crossmember
transmission mount
transmission slip yoke - how to size this?
dip stick - any suggestions on which one?
U joint - how to size this?
output shaft seal
torque convertor
6AN PTFE lines and connectors
main transmission harness from PCM to transmission
speed sensor harness from PCM to transmission
cut "ears" off the transmission to ensure enough clearance for install

drive shaft - this needs to be measured after I have the transmission in, but I estimate it will need to be 2" shorter than the current one. What other measurements should I take into account when getting a new drive shaft?

what is needed to connect the drive shaft to the rear end? new u-joint? yoke?

How would you check a used 4L80e to see if it would even work before installing it? I was going to drop the pan and see if I could find any major debris, but other than that I am going into this blind.

Sorry for the newbie questions, I have never swapped a transmission before, let alone from one model to another model transmission.

 

[Malibu795]

4l80 runs a 32 spline tailshaft vs 27
I'd jump to a full 1350/3" 083 driveshaft..
1350/32spline yokes are very common
When I still had stock 7.5 in the back I had a 1350/1310 3" driveshaft.. once I upgraded to a bigger axle I swapped the diff yoke to a 1350 a long with the 1310 on the driveshaft to 1350 as well and had it rebalanced.

Going to the -6 an line will need a short and long adapter need about ~15' of line if you're not running through the radiator, ~20' if running radiator and air cooler

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Pending exhaust you don't need to cut the side ears off.

Whats the current trans cross member? 4l80 need the extension.. UMI just released a fully adjustable x member.

UMI Performance 3108-R UMI Performance Transmission Crossmembers | Summit Racing

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Outside having it dyno tested, pull pan check fluid color and debris is best thing you can do.

Is the 5.3 ran off an OEM PCM? Staying that or going to a stand alone aftermarket?
Personally I lean towards Edelbrock/FAST/TCI vs Holley owned stuff

id run a flexible dipstick tube for ease of routing vs pre-bent tube..
I like lokar's stuff though they run about 160 summit/jegs has knock offs for about 1/2

 

[paradigm]

4l80 runs a 32 spline tailshaft vs 27
I'd jump to a full 1350/3" 083 driveshaft..
1350/32spline yokes are very common
When I still had stock 7.5 in the back I had a 1350/1310 3" driveshaft.. once I upgraded to a bigger axle I swapped the diff yoke to a 1350 a long with the 1310 on the driveshaft to 1350 as well and had it rebalanced.

Going to the -6 an line will need a short and long adapter need about ~15' of line if you're not running through the radiator, ~20' if running radiator and air cooler

ICT Billet 551124 ICT Billet Transmission Line Adapters | Summit Racing

Free Shipping - ICT Billet Transmission Line Adapters with qualifying orders of $109. Shop Transmission Line Adapter Fittings at Summit Racing.

www.summitracing.com

Pending exhaust you don't need to cut the side ears off.

Whats the current trans cross member? 4l80 need the extension.. UMI just released a fully adjustable x member.

UMI Performance 3108-R UMI Performance Transmission Crossmembers | Summit Racing

Free Shipping - UMI Performance Transmission Crossmembers with qualifying orders of $109. Shop Transmission Crossmembers at Summit Racing.

www.summitracing.com

Outside having it dyno tested, pull pan check fluid color and debris is best thing you can do.

Is the 5.3 ran off an OEM PCM? Staying that or going to a stand alone aftermarket?
Personally I lean towards Edelbrock/FAST/TCI vs Holley owned stuff

id run a flexible dipstick tube for ease of routing vs pre-bent tube..
I like lokar's stuff though they run about 160 summit/jegs has knock offs for about 1/2

Thanks for the tips.

The current crossmember is a Gforce designed for the 4L60 / 700R4 which appears to be different than the one for the 4L80. I am assuming I need a new crossmember?

5.3 is running off OEM PCM. I am going to pin it for the 4L80, currently it has no harness for the 4L60e or 4L80e, nor does it have one for the second speed sensor for the transmission. The wire harness was setup by PSI conversions for a 700R4, T56 or other non electronic setup.

I ordered this 32 spine 1350 Yoke:

https://www.amazon.com/dp/B08SVPZRF4?tag=gbody-20

I ordered this this crossmember:

https://www.amazon.com/dp/B0CKGTNCTC?tag=gbody-20

I ordered this 6an kit with 2x 70" lines, i felt that was long enough to go from the transmission cooling ports back to the passenger side of the radiator:

https://www.amazon.com/dp/B09PNQNHGC?tag=gbody-20

I ordered a flexible dipstick from Amazon:

https://www.amazon.com/dp/B00BGG9R0G?tag=gbody-20

I need to determine my u-joints, tail shaft, and then measure and order my driveshaft or cut existing drive shaft once the new transmission goes in.

Also should I be looking to replace my flexplate with one with a spacer like this?

https://www.amazon.com/dp/B000C8PD1G?tag=gbody-20

 

[Malibu795]

70" "should" be long enough.. remember one line is going from basically the back of the transmission to ~8" in front of the water pump and not in a straight line.


You might need a new one
Measure from bell housing face to trans mount center..

 

[64nailhead]

Holy moly - a lot of questions lol!

Use the stock 80e output yoke, then use your current driveshaft (if in good condition) and combination UJ’s as required. The driveshaft length should be measured and modified for your car. Yes, cut off the ‘ears’. Crossmember - use whatever you have and cut it to fit - don’t overthink the crossmember if you have access to a welder and cutoff tool (4 1/2” angle grinder). I’m not an OEM ECU person, so I have no input on that. Flexplate - 100% depends on what converter you are going to use. There are oodles of options available but they are dependent on what converter you will use and the spacing of that converter’s flexplate pads. It will require some measuring and possibly shimming. Regarding the condition of the transmission you bought, it’s a crap shoot. If the pan is full of burnt fluid and debris, then it should be rebuilt. If it came from a known good operational vehicle, then it should work as well as it was functioning when it was pulled. The upside to an 80e is that stock rebuild is $800-1200 and a stock 80 built to stock specs is good to 800 whp every day all day long.

For reference, I'm using a stock internal 80e that’s been properly rebuilt with a quality set of clutches and steels, gat 1100+ whp with an aftermarket valve body. I had it gone through during the winter of ‘22/‘23 and it works perfectly. These damn things are bulletproof.

 

[Supercharged111]

Once pinned for a 4L80, the stock PCM won't operate the 4L80 properly until the PCM has had a 4L80 segment swap. Not sure if you were tracking that or not. If you need to drive it to get it flashed, best to leave the trans unplugged and chug along in 2nd gear which is what it will default to.