I'm looking into buying an h3 with the 5.3 engine/ transmission swap, it drives and runs great but all the dash lights are on, would this be due to the pcm not being reprogrammed? Would this cause any damage to the drivetrain or cause any other issues?

 

are you willing to tackle all the electrical issues and incompatibilities that you have nothing to compare too since you did not wire it?

 

I suppose my question is how difficult of a job that is or how much it would cost to have someone else do it for me?

 

it would cost probably the same as what you pay for the truck in the end.
donor vehicle plus labour and parts. since they do not sell origional harnesses. it is not like it used to be in the 1970's the H3 has modules that need to talk to each other. (left hand wants to know what the right hand is doing then shake on it.)
well it could be the 1970's if you just remove all modern features. jimmy rigging windows and switch to manual seats. hardwire all lighting. and retrofir a wiper motor.

 

If you are asking, then you would have zero idea what you are doing. I say jump in with both feet so long as you have a near endless pile of cash to pay somebody to figure out the puzzle that has no directions, no knowledge of what was done and what was skipped, and will be glad to make your pile of cash much smaller. There are shops out there that do the swaps in the H3 and donor motor you supply, $10K plus.

Just buy an Alpha. If you know how to buy a used vehicle, turn key & no issues.

 

Worst-Case Scenario:

 

LOL! that's not too bad ...