I Really want to do a LS swap but I have basically a new engine and transmission right now!! I wouldn't mind using my th400 with my 5.3 but not sure if it will work. What do u all think???

 

I would use what you have and save up for a boosted 5.3 truck engine or build one slowly while you use what you have.

 

That is without a doubt what I "should" do.... BUT I personally never do what I should do.. Its that "want" in me that always gets it way.... lol

 

Your transmission will work with the 5.3. Just need some minor adaptations. I was in the same boat. Had everything in my build towards using a 5.7 SBC. Was lucky enough to find someone who paid me exactly what I had in it. Now I'm installing a 5.3.

 

after plenty of research, I am going to run a LQ9 with a 4L80E turboed.. all with a few stock LS upgraged and thats it... Thats all I will need IMHO!