I got a few questions for you guys! I got a 2012 Silverado 1500 4x4 6.2L I'm going to be going to a lq9 408 stroker and want to put a 4l80 behind it. Has anyone done this and got their dash reprogrammed to read PRND321 instead of the stock PRNDM? It would be nice to be able to manual shift it when you come up to some cars that think they are fast and does anyone know for sure that my transfer case from the 6l80 will bolt up to the 4l80? I'm pretty sure they're the same spline but not sure on the bolt pattern on the tail shaft. Thanks!

 

The 6l80 should have the same 32 spline output as the 4l80, as shoukd the bolt patterns be the same!! what are you gonna do with the 6l80 after the swap??? As far as the dash goes that should be fairly straight forward but your best bet would propably be to add the 4l60 tcm and probably swap harnesses in the process.... Make life easier, i know the 4.8 trucks up to 13 had 4l60s in them so reflashing the ipc shouldnt be too big of a deal i wouldnt think....may wanna swap your shifter stalk also, do away with tu/td button

 

Thanks! I'm not sure if I'll keep the 6l80 or sell it... I have a circle d 3400 stall multi disk in the 6l80 too. And I see that pcm or nc has a 6l80 to 4l80 conversion harness and tcm seems to be the easy way haha. And as for the shifter stalk that won't bother me I'll leave that in if I ever go back to the 6l80. Do you know if the trans mount is the same on the 4l80? And will the cross member be the same or will I have to do some cutting and welding to make the crossmember work? Thanks

 

Going from a 6l80 to a 4l80 is going to be from my understanding a lot like the 4l60 to 4l80 swap, as i understand it the 4wd trucks use the same crossmember for the 6l80 and 4l60 as theres only maybe 3/4 of an inch difference in case length, where as the 4l80 is almost 2" longer..... I was asking about your 6l80 because im looking for one for my yukon, but if youve already got a stall for it, you probably arent going to want to let it go...

 

I'm in the process right now of swapping my 6l80 to a 4l80. I'm using the Pam of nc conversion harness as well. 4l80 is only 1 inch longer then the 6l80 so very little modification is needed to the trans crossmember. The trans mount from the 6l80 bolts directly to the 4l80 mount. Also the transfer case bolts right up and has the same spline count between the 6l80 and 4l80. I haven't finished the truck yet but will be seeing about fixing that PRNDM on the cluster and see what I need to do to make it read PRND321. I keep my page on FB pretty updated and have tons of pictures if your interested. Three6GMC is the page name.

 

Thanks! I have the trans, t case and converter out of the truck already and am going to be pulling the motor this week/weekend sometime. It's getting a lq9 408 stroker. I will keep you in mind if I do sell it! How soon are you looking for one? I would probably keep it a few weeks after I finish it all up to make sure I like the 4l80 but I'm sure I will my last truck had a 4l60

 

Thanks a lot great info! I will go look you up on fb now! Do you need a shorter rear and a longer front driveshaft as well with the swap?

 

I believe so only being that the trans is an inch longer. Haven't test fit the driveshafts yet. I'm getting new shafts by Texas Driveshafts Specialties in San Antonio anyways so will double heck the measurements when I place my order.

 

Whenever, depends on price and finances at the time....4l80 will shift similar to the 6l80 more so than the 4l60 at least way it feels anyway....nither have the 1-2 shift drastic gear change drop off...

 

If you're looking for one now I saw that three6gmc is selling his 6l80