looking at a 1999 hi 49000 mile h1 build date of july 1999 how long were the 6.5 block issues going on for also looking at a 1994 na with 29000 miles. looking for opinions on which would be the better rig? thanks mike

 

The suspect blocks were around through the end of 2000 even though not all of the blocks were bad. My 2000 slantback was a very late production truck and it had a block in the suspect range even though I never had any issues with it.
The 94 with the NA motor will be bullet proof. Very simple, no issue arrangement. It also doesn't accelerate very fast and probably won't run as fast on the highway once you are up to speed.