My truck cranks but won't start

Computer syse

How many miles? Is it a 3 valve? Did it have the death rattle from the timing chain tensioners the last time it ran if it's a 3 valve? Any codes?

I suggest you reconsider throwing parts at the problem hoping you hit the right one, it gets expensive. Check the coil(s) to see if they are good. Use an HEI to check each plug wire to make sure they are firing. Use a fuel pressure gauge to check the PSI at the rail with the engine off, key in the on position. Your goal is to eliminate possible causes for the non-start condition.