L94 & 6L80 Into My '92 2dr K1500 Blazer

Long time lurker here; first post. I've studied this swap for about a year now and recently acquired a 2012 L94 6.2L with 5 miles on it. The 6L80 is out of an identically optioned 2012 Denali; it has 10K for mileage. The engine swap won't happen till probably March. I'm hoping to get most of the parts on hand and knowledge in my head before then. I'm hoping the swap itself won't take more than a month. (This won't be my first engine swap, but it will be my first LS swap.) My plan is to keep the motor and trans as close to stock as possible. My intent is to keep the BCM in the mix for cruise and "tow" mode.

I've owned the '92 since it was 6 months old. It's in pretty darned good shape, but the tranny is getting tired. I've already swapped in a freshly built 14 bolt SF rear end with an Eaton Trutrac. 3.73 gears. Once the engine swap is done, I'll redo the interior--although Infiniti G37 seats are going in this fall, before the engine swap--then I'll re-paint to finish it off.

My first question regards the 6L80. I understand it's about an inch shorter than the 700R4. I know most folks use 1" setback mounts to get the trans in the right place, but that won't be enough here. Is there enough room to put the motor far enough back to use stock driveshafts? If not, what setback is a good compromise for access to the rear of the engine? (I'll be using electric fans.) Also, has anyone dropped a LS motor with a 6L80 already attached into an OBS truck like this? If it fits easy enough, that seems like it would be a lot easier than getting the trans in place afterwards...

Thanks in advance for any and all advice!
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Okey dokey, I guess not much experience putting a 6L80 into an OBS truck here. I'll post what I learn as I go along to help the next guy out. :) Talked to PSwired--Patrick--from another forum. He's done the 6L80 into an OBS and graciously spent 30 minutes on the phone with me. Many thanks to him for his time and expertise.

I could maybe get the rod type shift linkage to work. (The '92 has rod linkage, the '95 has a cable shifter. Not sure which year is the changeover.) Doesn't seem like it's worth the effort at this point. I'll start out using an Ididit cable adapter for the stock column shifter, and possibly switch to a 2012 Malibu floor shifter with Tap up-down buttons later. I'm going to have Motech out of Vegas do the ECM programming and use their BCM setup for cruise control and tap up-down shifting. That'll keep everything as stock as possible.

I'm just here to learn! This is going to be an interesting swap....:tacos::tacos:

Thanks! Nothing too interesting will happen till March; that's when the swap begins. (Planned...) Right now I'm trying to amass information and parts. I have the engine & trans & complete set of GM service manuals for both the '92 and the 2012 now; trying to figure out the transfer case before buying one of those.

I'm thinking NP246 as the rig will only be lightly four wheeled. However, I have to figure out how the E38 ECM will figure out the transfer case is in low range. According to the Service manual the E38 looks at the VSS from both the 6L80 and the back of the transfer case, as well as getting a "low range" signal over the CAN bus from the transfer case. Of course, the NP246 can't send a message over CAN. I'm trying to find out if the E38 can be tuned to ignore the CAN bus signal and just use the speed signals. (BTW, the 6L80 has internal front and rear speed sensors--even for the 4WD version.) OR, does the trans shift based on it's own speed sensors? Does the E38 even need to know "low range" when paired with a 6L80?

Getting close! I have to finish my basement remodel first, should be done in a week or two. Then I can put away all of my wood working tools and get ready for the engine swap.

I'm sticking with the original NP241 Transfer case. Looks like I should just need a new input gear to match the 6L80. Measuring the 6L80 it's just about identical in length to my 700R4, so I should be good with the stock drive shafts and TC shift linkage.

I've collected most of my parts:
-Wire harness from Motech complete with BCM for stock cruise control, tap shifting and Tow mode.
-New Gas tank from a 1998 Yukon. That allows me to use a '98 fuel sender/pump. The '98 uses the correct resistance range for the fuel sender. It also has a fitting for a fuel tank vapor pressure sender.
-'98 fuel sender/pump assembly
-2001 Corvette Fuel Filter/pressure regulator
-2012 truck air cleaner/MAF/intake plumbing and electric fans
-motor mounts
-Holley AC brackets

Still need:
-IdidIt conversion to cable shifting.
-Fuel lines and fittings
-oil cooler & trans cooler & lines and fittings.
-EVAP setup.
-PCV catch Can
-input gear for the NP241

-Exhaust: Still undecided. I'm getting a bid for a complete exhaust from "Get Bent" here in Portland, Oregon. Steve, the owner, has given me a ball park figure of $1800 for a mandrel bent stainless steel exhaust complete from the exhaust manifolds back. (Including two cats.) I'll have a firm price after he gets the truck on a lift and we agree on exactly what the exhaust will look like. I would love to hear any advice on exhaust you guys have!

Big question mark here: How low will the stock oil pan sit? It looks to me like it will be the lowest thing by an inch or so. Anyone who's done this, PLEASE help me out here! I'm thinking I need a new pan, but all of the options I've seen are not compatible with DOD. (Yes I am running the DOD and VVT...) Where does the stock truck pan sit on these trucks? Any pictures? This truck will be driven off road occasionally, so ground clearance is an issue.

Thanks for any help in advance! I'll start getting up pictures in the next couple of weeks.

On my 2wd truck it sits about an inch and a half below front crossmember.

Thanks for the reply! Not good news though... Hopefully somebody with a 4x4 will reply. I've searched all over and can't find this bit of information. I'm sure it's on here somewhere, I just couldn't find it.

I wonder how much it would cost to slice off a bit of my pan? I hate to do that till I know I really need to...

$1800 is crazy expensive for your exhaust! I have a guy in Grants Pass, OR quote me $350 for 3" duals, balance pipe, magnaflo mufflers and the tail pipes tucked even with the corners of the bed. Granted that is just steel and without cats but high flow cats are another $200.

As far as your oil pan goes, you can section an inch out of it as I did on my 1990 p/u. You will lose one quart if oil capacity. I carefully cut the bottom off with a sawzall.retaining the drain plug,then measured up 1 inch and cut that section out and then found a guy to weld it back together.Then modify the oil pickup tube.Your oil pan not hang below the crossmember. Hope this helped.

Honestly I'm not sure how different the L94 is from the LQ9, but that's what I just put in my truck with no issues as far as the oil pan goes. Not sure if it makes a difference but I'm lifted 6" on 35" tires. I can get pics to you and possibly some measurements this weekend when I'm home, if that helps at all. All I know is that I have so much room everywhere it's like the truck was made for a bigger engine.