Official NBS 4.3v6 to GEN 3 V8 swap Guide

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i have sierra 2001 v6 4x2 AT ( 4l60e ) i want to swap to an LS1

this is my first GM car ( Japan user ) i live in saudi arabia i asked everbody about this swap no one have a clue about it

so here is My questions :

1- i did find an engine without harness & PCM
2- i find an engine harness from a 2001 sierra v8
3- also find an engine mount & frame mount
4- i find a flex plate & torque converter from a v8

q1 - do i have to change any interior harness ?
q2 - do i have to send my pcm over to allen or any tuner will help ?
q3- i have been told that the gearbox housing is not the same as a v8 ?
q4- do i have to change fuse box or just leave it as it is ?


i have been searching all over i didn't write this until i am 100% sure that i didn't find any answer to my questions

thanks to OP for his work and effort & everybody have been helping