Forgive me about this.
 

I hae done a search and can't find a definate answer and i am a noob to the LS motors but can someone tell me if the 5.3 and the LS1/LS6 blocks and heads all have the same dimensions? I know the heads and intakes are interchangable and that most of the 5.3 are cast blocks but are they physicaly the same size on the outside so if i were to make mounts or do a motor plate to install a 5.3 i could change to a LS1/LS6 later without having to redo everything? Also are the wire harnesses the same if they are the same year motors?

Thanks for helping a noob.

Swapping the engine will not be a problem. I started out builing a 5.3 and switched to an LS1. I am running an Escalade computer and altered harness on my LS1. Just like with any swap you are going to modify the harness.

Blocks and heads are the same size. 4.8 through 6.0(cathedral port motors)

Harness will be the same for either if you are going to use the car intake regardless of the motor. Main differences are injector connectors, MAP location and MAF connection (3 pin vs. 5 pin). Hope that helps.

Jon
PSI

Thanks for all the answers and Stancel i will see you tomorrow at Turner Field.