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I am using a 2005 version of the 4L80 on the 2015 5.3L. The bolt pattern for the 6L80 is different at the top of the bellhousing and the 4L80 is missing two of the top bolts that don't line up with the genV block. Some people don't mind this and bolt it up and send it. I don't like the no support at the top, so I made a "saddle" so I can use the top hole. It was kind of a pain, but looks like it will work. Made a pattern off the 6L80 and drilled the 80 bellhousing for the top bolt. this is 3/16 plate with the shape and holes drilled I will weld the 3/4" bushing with a 7/16" hole to the plate to fill the space in the bellhousing. This is how it looks finished I used 7/16" hex bolts and ground the heads down so they fit thru the unused holes. There is a step in the bellhousing hole to prevent the bolt head thru. Bolts after grinding I used some JBWeld to prevent them from turning when I tightened the nuts. Bolts installed Bolts installed--other side
This is about 1000% unnecessary
Neat execution on your idea...I'll give you that
But I don't want anybody reading to think this is in any way shape or form necessary for ANY power level
I did this for my own feel good. Has nothing to do with power level. Thanks for warning everybody.
And, Yeah--Nobody should do the stuff that I do. I will post up some rear suspension pics for you to comment on.
Last edited by dw456post; Nov 2, 2022 at 07:54 AM.
Don't take what I said sideways
I gave credit to the neat execution
But it's not going to benefit you in any appreciable way
I just didn't want people to read this post and think this is something needed for a swap
And we all do LOTS of things to vehicles that have no real value, but we like to do it anyway!
With the holes that match. there is 13" of bellhousing supported. The two holes that do not line up are 5". That means that 38% of the bellhousing is not supported. Argue with GM about why those two bolt holes are 1000% not needed. I am sure they would not have put them there if they were not needed. And I know that a lot of guys have used a 4l80 on an ls and skipped the top hole---I did it---it was only one fastener, not two.
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4L80E to Gen V 5.3 
