need 6.0 help, the truth..

[mopower440]

ok guys, someone has to know for sure, the 100% truth on this.. Heres the deal, i have a 1999 silverado extended cab shortbed 4x4 with the 4.8 engine and 4l60e trans, all original. I want to swap in a 6.0 and keep my 4l60e and stock torque convertor and all, will beef up the trans to hold up to the 6.0.
Ok, From what i have heard, in order to use my stock convertor and 4l60e, i need to find a 2001-up 6.0 to avoid the oddball longer crankshaft. ok, that would be no problem, but i read somewhere yesterday it needed to be a 2004-up to avoid the oddball longer crank, so back to the drawing board.. Does anyone know the truth? I know an LQ9 would bolt right up seeing as they were mated to 4l65e and 4l70e, but most likely it would be an lq4 that was mated to a 4l80e that i would use being as they are cheaper, but, will the lq4 work, even if it is newer than 2001 or will it STILL have the longer crank? I am looking at a 2004 lq4 out of a savanna van and another 2003 lq4 from a 2500 truck, will they work or will they have the dreaded longer crank? I dont wanna mess with having a custom convertor made or any of that, i just want to pull out the 4.8 and install the 6.0 and be done.. anyone know the truth? If all year lq4's will be a problem with the longer crank, i guess ill have to save longer for the lq9, need to know the truth before i buy anything..This is already being done on a tight budget and i sure dont want to order an engine and it not work without custom convertors and all.
Thanks
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[Mickeymotormount]

From what I have read, you should be good with an engine later than '01. I believe the 6.0 engines in the 99 and 00 trucks have the longer crank. Starting sometime in 01 they went to the shorter crank.

My 6.0 came from a 99 Silverado and it did have the longer crank. So bolting it up to an older 4L60E was not an issue for me.

[Blasphemy]

This quote is from advanceadapters.com and from my understanding, you only really need a spacer to fit the older style gen I blocks. But if you already have the "LS style" 4.8 block, than a 6.0 is the same bolt pattern and you shouldn't have an issue. When you take out the 4.8 just do all the necessary depth measurements on it AND the donor 6.0 and make sure your donor engine comes with the flexplate attached. At least you have a lot of the same wiring connections and won't have to do a lot of modification and integration to get things working.

"Since the LS series flexplate only fits a LS series block and the engine crank is recessed .400”, there are a few unique things
about the torque converter that bolt to the flexplate. The spacing of the flexplate from the back of the block is the same as
early GM blocks. The flexplate is dished out .400” to compensate for the crank. The difference comes into play with regard
to the bolt pattern of the torque converter to the flexplate and the snout length of the torque converter. A GM transmission
coupled to a LS series block has a longer pilot snout to compensate for the LS series crank and a different torque converter-
to-flexplate bolt pattern than any other GM torque converter.
Two things are required when using a early transmission to a LS series engine. First, the stock flexplate must be drilled to
fit a common/standard style GM torque converter. Second is the snout length of the torque converter. The 716155A crank
spacer will compensate for the shorter engine crank.
Note: we have seen a few aftermarket torque converters that may require the crank spacer to be shortened slightly, It is very
rare and you would notice it by having a .100+/- gap between the flexplate and torque converter once the convert has been
pull forward from the transmission pump.
The only time that these items will not be an issue is when a customer is retaining the stock transmission that was coupled
to the LS series block. These parts will be necessary even on some new 4L60E transmissions with the removable bellhous-
ing.
Our kits include a new flexplate and it may not work on
all LS series engines.
The 6.0 engine with cast iron heads should only be used
with the stock automatic transmission because there is
no way of re-drilling the stock flexplate due to the dif-
ferent crank stickout.
The 4.8 engine coupled only to a stock manual trans-
mission in 1999 to 2003 does not have the recessed
crank. This kit can not be used this 4.8L engine.
LS7/LS9/LSA/LSX engines all have 8 or 9 bolts that
hold the flexplate to the engine crank. Our kit is not
compatible with these engines."