LS to TH400

[Psycho71]

Hi All,

I have done some searching, and cannot run across the info I seek w/o interpreting excerpts from several other threads to arrive at a conclusion. I'd like to see if I can get some straight up answers to the questions I have before I start assembling info that might or might not be completely accurate for my application.

I have an '85 K20 Suburban. Good running 350, th400 trans, w/NP208 transfer case. Fuel is eating me alive, and I have another project in which the 350 could be of good use. So I am looking at my options on either a diesel, or an LS swap. Diesel has it's appeal, but too in depth for a diesel that will make any larger amounts of torque. So the LS swap is what I'm looking at now. Mostly looking at the 5.3 liter.

I am wanting to continue using my transmission, transfer case, and remaining drive-line parts. All are in great condition, and do not need any work.

* What is involved in connecting the LS engine to the th400?
* Any controllers, sensors, add-ons of any kind I'd have to run to make these two jive together?
* Will my mounting points stay the same? Crossmember mainly?
* Will I be able to re-use the torque converter I have now?

On the LS swap itself;
* Any comprehensive lists, part numbers helpful, that reflect the necessary items I would need to swap an LS into my burb?
* What is everyone doing about guages when doing an LS swap? not really looking to go all out wish the new dash components and all that. Just want an EFI engine with good reliability.
* Will there be any issue with running my trans, speedo gear, with the cable as OEM equipped? Or will the LS engine/ECM need some kind of signal input for this?
* What all would I need off the donor truck to complete this swap as far as I possibly could? Yes, i want to go back with the EFI as well.
* Any issues I might not be looking at that I should be?

I'm not looking to modify the LS engine any at all, at this point. Looking to keep the swap as simple as I can, as economical as I can, and as reliable as I can. I know w/o the OD trans, my mileage will suffer a bit. But compared to what I'm getting now, it can only improve. Mianly I want something in there with a decent amount of torque, reliability, and a few more MPG's than I get now.

Thanks for any help or insight y'all can provide. I am an old school gear head myself. The new platforms are a bit foreign to me, but more than willing to learn about them.

Thanks for you time and patience.