Engine Replacment query. Hi All, I need some guide from experiance ppl in desideing the best option to replace an engine. I have the 08 Sierra 1500 with the 5.3 engine LY5 (non flexy fule), 4 speed ( 4L6E or 4L65 Not sure but rated at 7000 GVWR) , and I want to replace my engine with something STANDERED, with no modefication, so I wish some one could help me in this , how hard is this going to be, what do i need to change, what programming is requiered to the PCM and TCM, is the wiring good or I will need major wiring in order to operat the following options : ( if heads or mainfold or any major component will not fit let me knw please ) TO install a complete L92 ( the vortch vr of LS3 ) 6.2 form an escalid or a GMC Denali , i gusee my stock tranny will need to be changed, L98 ( LS2 ) 6000 out of a Holden or Caprice SS, or the L76 of a HD truck Do you think it will requier mods to the interior of the car ( 4WD options and gear indicator) If and probably will need to change the tranny, which one should I chose ? 4L80E or 4L85E i gusse will be easy to fit, I dont have havvy towing but i do speed more than 120MPH. 6L80 ( is it elctronic or no ) or 6L90, /I gusse this will creat some problem since my truck is set for 4 speed only. I have a plan to install a Magna charger few months later, so will need to keep this in miend while chosing the transmission. I will really apprecate good help. Thanks to every one who bothered to read this far.