I have a 94 blazer, WHen shifting from 1st to 2nd it tends to snap you neck back. Then after that runs good. This happens everytime from 1st to 2nd also when you swith from part to drive it jolts forward.

My question is this an Indication my shift servo is crapping out or is it time for a new tranny or rebuild

 

Sounds like someone has put a shift kit into the vehicle. They could have installed an after market servo as well... I would not say that it is an indication of anything going out if it is consistent.