LS Swap in a stock-height '72 4x4?

[joeydurango]

I'm planning to do a 5.3 LS swap in my 1972 K10. The truck isn't lifted or lowered, just the stock height. I've heard some folks claim you can't LS swap into a stock-height 4x4 because of clearance issues between the oil pan and differential. The guys at Pacific Fabrication - who seem super-knowledgeable and friendly, by the way - say the swap will work fine with their 4x4 crossmember and their low-height LS oil pan. I trust their experience, but wondered if anyone here had done what I'm about to do, just to confirm it can work. Anyone out there with the same conversion?

[crazy longhorn]

The sump on the truck pan is deep....but to the rear. I would think it would fit, but can not say for sure? I opted for the GMPP hotrod pan kit , on my 2wd ($145, through summit or jegs). If it were mine, I would do a trial fit with the stock pan, then make the decision on parts? Longhorn

[joeydurango]

Besides the engine oil pan/differential potential issues, I'm now being told of potential 4L60e transmission oil pan/front driveshaft clearance issues on stock-height 4x4s. I'll search around for info on this - first I've heard - but same question, anyone have experience on this? We're keeping the NP205 and using the 4L60e adaptor. Thanks!

[72 Copper C-10]

people may be telling you wrong, i want to do a 5.3 or a 6.0 swap on my stock height 72 4x4 and i haven't heard that, look at wasted income's build thread about his 69' k10 for his dad. and a 4l60e is basically a electronically controlled 700R4, you shouldn't have issues.

[ls1nova71]

Thealien put one in a 4x4 Jimmy, pretty sure its stock height. He has a bunch of info here. http://67-72chevytrucks.com/vboard/s...d.php?t=377348 Might be something in there, but you'll have to look for yourself.

[joeydurango]

LS1, yep, I've been looking through a bunch of TheAlien's threads, he seems to have a lot of info. I've been on that LS Swap thread of his more than a few times. After digging around a little more, looks like he notched his pan for the Jimmy project. Anyone know of or use a "low profile" pan that doesn't require notching? I haven't seen anything like that, although I've been looking.

And 72 Copper, if I were you I'd dig around a little more before starting your swap, because there are lots of photos floating around of pans with no driveshaft clearance. Also lots of photos floating around of pans with hammered-in corners... If you get yours going soon, let me know what you find out. I'm curious. I'll do the same if I get started first.

[72 Copper C-10]

Originally Posted by joeydurango

LS1, yep, I've been looking through a bunch of TheAlien's threads, he seems to have a lot of info. I've been on that LS Swap thread of his more than a few times. After digging around a little more, looks like he notched his pan for the Jimmy project. Anyone know of or use a "low profile" pan that doesn't require notching? I haven't seen anything like that, although I've been looking.

And 72 Copper, if I were you I'd dig around a little more before starting your swap, because there are lots of photos floating around of pans with no driveshaft clearance. Also lots of photos floating around of pans with hammered-in corners... If you get yours going soon, let me know what you find out. I'm curious. I'll do the same if I get started first.

Awesome!!! thanks!

[joeydurango]

Just an update - talked extensively with Pacific Fabrication, the guys that are building our swap package. They do a lot of swaps in-house, and they've seen a bunch of different things. What I was told regarding potential clearance issues is that IF the original leaf springs and bump stops are in good shape, the low-profile engine oil pan *should* clear the front differential. They recommend, however, a 2" lift to ensure no issues.

As for the tranny oil pan, they recommend a small-tube driveshaft. I'm not positive this will actually help, as it appears the CV joint is actually what's interfering with the pan, not the shaft itself. At this point, we're just going to go for it, and if it doesn't fit, then we'll work on a mild lift and notching the pan or some such. It can be done... just not necessarily easily.

It's odd, but TheAlien's build needed tranny pan notching. FirebirdJones built out the same exact thing, and needed no modification whatsoever. I'd love to know what's going on there.

[jamesjones]

You shouldn't have an issue if you get it up as tight against the firewall as possible. I have a roughly 5" lift and here's the clearance...

[jamesjones]

Come to think of it you shouldn't have a problem at all. The diff is off to the side so even the truck pan shouldn't be that bad but a FBody pan would probably be money. Here's a picture with my suspension on the bump stops and you can see the diff is out of the way...

[joeydurango]

Thanks for the photos. Under our truck even the current 350 pan is pretty close to the diff. We are using a low-profile pan on the LS engine, so we'll just have to see how it goes... we'll find out in the next few weeks! At this point I'm more curious about the transmission pan, things could get interesting.

I'll keep updating with what we run into, for those looking to do the same swap.

[joeydurango]

Just an update on this - finally have most everything together and we tried putting everything in today. Keeping the t-case in the stock location, with an Advance Adaptors part for the 4L60e, and using a 2002 LS 5.3, the Pacific Fab crossmember doesn't have enough clearance to the differential. Oil pan to diff should be fine, but the crossmember itself will bottom out on the diff with any decent suspension compression. Can't really move the engine back any further - not much room up against the firewall. User FirebirdJones somehow did the same swap in a stock-height truck with no issues, but maybe he replaced the springs or something - after 42 years, you'd think there would be some sag in the original leaves. Working on a solution, will post up with results.

[joeydurango]

Did hours of research and tried to get some measurements on various trucks yesterday to solve this problem. Just for the benefit of anyone facing this same issue later - I don't believe an LS swap with the Pacific Fab crossmember will work in a stock-height 4x4. Nothing wrong with the crossmember, there's just not enough room above the front diff and the crossmember is a pretty tight fit to the pan. Gotta note that Pac Fab DID say that the swap *should* work with a stock height truck with good springs - not what I found at all, see below.

As far as I can tell from research and measurements, the stock front suspension should have about 4" of travel. We're sitting, on original springs, with only about 3/4" clearance between crossmember and diff. I figured out via a few measurements on other trucks that our original springs have sagged about 1 1/2", so if we went with stock new springs, we still would only have 2 1/4" of clearance, not nearly enough for normal suspension travel. End of story (for now): There's a TC 2" lift kit on the way. Should work great, we'll see how it goes in the real world.

User FirebirdJones somehow did this same swap into a stock-height '72 Jimmy, with the same crossmember... all I can figure is that he doesn't have full suspension travel. That's what it looks like in his build thread too - a shot from underneath showing the diff and crossmember has nowhere near 4" of clearance.

[Nitis]

Any update on this build?

[joeydurango]

Still working on it... but it will have 2" of lift. Should be running in the next week or so!