Opinions on tricky suspension situation, please...

[joeydurango]

Doing an LS 5.3/4L60e swap into my 1972 K10. Truck is currently stock height with original springs and bushings. Wanted to keep the truck stock height, but on the 4x4 we're running into problems with front diff clearance. Using the stock transfer case location (therefore engine fore-aft is set), using Pacific Fab's 4x4 LS crossmember (fits great in the truck, but doesn't have enough clearance from diff to crossmember if suspension is even partially compressed). So, we have to increase that xmember-diff distance somehow.

My question is: Judging from the info above and the photo below, what are your folks' opinions on how to best remedy the problem?

1. Spring blocks/spacers/whatever they're called - cheap, easy, but probably some downsides? No heavy-duty off road for this truck - will be a daily driver with light off-road use.

2. Small lift kit - 2" or so. Would like to avoid if at all possible... but if you have a photo of a 2" lift truck, post it up.

3. Curious about opinions on this train of thought: I figure that even though the truck sits pretty nicely right now, 42 years of fatigue on those leaf springs has to mean some sag. So I'm wondering what new stock-height springs and new bushings would do to increase the xmember-diff clearance. Any educated guesses on this, given how the truck sits in the photo? 31" tires in the photo. The current front leaf springs, when the engine is in the truck, are significantly negative arch. Not sure if new stock-height springs are negative arch or flat.

4. Finally, curious about having Alcan up in GJ fab some springs for the truck that are slightly "taller" than a stock spring would be. Pricey though.

Any opinions welcome, especially if you've got experience with this type of thing in particular...

[1968k10blue]

As a fellow k10 owner I have contemplated this swap and wondered if this would be an issue, other than what you mention, the only thing I can think of would be raise the engine, but that would probably cause yoke angle issues, or maybe a shorter oil pan? no clue if the oil pickup would be able to be that compact or if there is an oil pan small enough just a thought.

[joeydurango]

The pan isn't the issue - we're using a low-profile oil pan that has plenty of room (knock on wood!). It's the crossmember itself, and it's a tight fit to the pan, so no room for improvement there. The crossmember is also a pretty tight fit inside the frame rails, vertically, and we've got it up against the top of the rails. Unfortunately, I think we have to lift the truck somehow. I just don't know whether to put in an actual lift kit or if putting in new stock-height everything will gain us the necessary couple inches.

[1968k10blue]

Then, wouldn't you be able to use the stock xmember? I know you would need adapters for the mounts but that might be a good option if you can still return the custom one and if you still have the original. Oil pan clearance is really the only reason to use an aftermarket xmember right? I could and probably am wrong in that one, but once again just throwing out ideas here.

[joeydurango]

Stock xmember can work fine with different mounts on 2wd trucks. 4x4 is another story - the stock xmember isn't wide enough for the lowest-profile LS oil pan. So yes, gotta use an aftermarket xmember.

[1968k10blue]

I Guess I am pig of Ideas then, I would go check the 4x4 section, they usually can he low there are alot of 67-72's over there

[joeydurango]

No worries, thanks for the input! Getting all the variables down is confusing, believe me.

[mongoose]

call the company.. who sells a product like that? is it normal? how much clearance was with the stock member?

[joeydurango]

Yeah, it's completely normal. No problem with the xmember - it's doing exactly what it's supposed to do, making it possible to fit an LS engine in a '72 4x4 frame. Most people doing the LS swap in a 4x4 just lift it and be done with it. My problem isn't with the engine, or xmember, or any of that. I'm mostly trying to determine how much stock leaf springs can be expected to sag over 40+ years... I would hate to put a 2" lift on, only to find the truck 4" higher than it was...