I have two different blazers would it be easy to do a swap they are both ls does that make a difference?

 

The LS is just a trim package designation. Yes they will interchange, though a few external parts may be different(exhaust manifolds, egr, secondary air pump, things like that) but the engines themselves will interchange. Just watch out for little differences like I mentioned and make sure to use the ones off your truck if you do see a difference.