ok here is my problem,got up one morning to drive my 94 blazer(vortec 4.3)4wd and had no first or overdrive,not slipping just like its gone i have 2nd 3rd an reverse,so here is what i have done so far changed solenoid a,fluid an filter,ignition switch still no change,any ideas does the trans have its on computer,i don't know any help would be greatly appreciated

 

This condition points to something amiss with the 1-2 Shift Solenoid Valve (367A). This could be sediment in the valve, faulty electrical connection, and/or a damaged seal on the valve.

The image below will show you which one is the 1-2 Shift Solenoid Valve (367A):

 

yea i changed the 3764 a solenoid don't know were to go next,any suggestions