In the process

[Jamesgcoffey65]

I'm doing a swap before the first time I have a 96 k2500 with a 4l80e and a 99 ls out of a GMC my question is I'm I going to need a bushing inorder to mate the 99 engine to the 96 transmission

 

[MrMarty51]

I am not familiar with the bell housing bolt pattern on the LS engines, but, if it is the same as the old cast iron V8s and six cylinder engines then not. No adaptors is needed.
Just be sure that You have the proper torque convertor and flex plate to match the LS engine.

Welcome to the forum James. There is a bunch of generations old ranchers over here named Coffee. Mostly southward of here out in the more mountainous region along the Tongue River Road.

 

[dbrannon79]

Welcome to the forum @Jamesgcoffey65

what engine are you working with? iirc most of them that year range were the same bolt pattern but the gasser LS motors might be different. now for the 350 (5.7L) , 305 (5.0L), and the 6.5 diesels are all the same pattern only some used a center top bolt where others didn't but will still bolt up.

 

[Jamesgcoffey65]

Thanks for the reply. The engine that is going in is a 99. 6.0 ls. The one that came out is a 5.7

 

[MrMarty51]

Thanks for the reply. The engine that is going in is a 99. 6.0 ls. The one that came out is a 5.7

The back of the engines, where the bell housings bolt to the engine, do they look the same betwen the 5.7 and the 6.0 ?
If the physical appearance is the seme then the 6.0 will bolt to the 4L80E transmission.

 

[dbrannon79]

I think it should work. my good friend has a 03 box truck that has a 6.0 with a 4l80e. You will need to transfer the ECM and harness with the engine and need the harness for the trans too connectors could possibly be different between the years. @THEFERMANATOR can tell you everything and anything you want to know between the two year differences.

 

[dbrannon79]

those 6.0 GM engines are a beast when it comes to power!! my friends box truck has a bad engine and only runs on 5 cylinders but in a 1 ton dually express van chassis it can still burn rubber running as bad as it does!!

 

[NVW]

Try one in a Yukon Denali, it's a quick little vehicle.

 

[razur65]

Thanks for the reply. The engine that is going in is a 99. 6.0 ls. The one that came out is a 5.7

You've signed up for a for a few more issues than flex plate / bushing alignment. ICT Billet has a great page with swap info and even references the differences in the crankshaft end dimensions. https://www.ictbillet.com/swap-guide/ls-swap-guide.html#cat-567