1999 k2500 7.4 camshaft offset

[markaria]

Hoping to get someone to chime in on this to help me get my plow truck running correctly... I have done a bunch of work to this 1999 vortec 454 and am about to replace the plastic crap distributor with a new  aluminum one but I am concerned in being able to read the camshaft offset. I know the procedure welI as I also have a 1996 tahoe (5.7 vortec ) that i have done this job on before with my scanner.

My scanner is an autoxray ezscan 6000 which had no problem showing me the cam retard on my 1996 5.7... HOWEVER on the 1999 7.4 it does not show up at all and there are definitely quite a few less paramaters that i can see with the 7.4.  I am wondering how/why this is possible. Id prefer not to pull the old distributor without being able to reset it correctly and am aware that i can do this the trial and error/code reset way, but  It just doesnt make sense to me that i have this discrepency with 2 of the same generation trucks (gmt400) where one works with my scanner and one doesnt... Anyone out there have an idea why? Is the computer different on the gmt400 7.4 vs 5.7? If my old distributor had a bad cam sensor or wiring to it would it just not show? I dont have a check engine light but the truck does a poor job under more than half throttle, surges/hesitates etc...I have already installed new fuel pump/injectors/wires/plugs cap/rotor and havecats removed for testing since they were suspect from old injectors leaking down.

Thanks