Transmission problems
 

I purchased a 2004 trailblazer was not shifting right and service 4wd light came on when I tried to put in 4wd, so pulled pan on transmission changed 2 shift solenoids new filter put back on road drove a couple days then would not shift into 3rd gear, bought a tranny from an 06 tb put it in and got no gears at all was not pumping any fluid but the 4wd service light went out and it would go into 4 hi and 4 low, so I pulled that tranny out, changed all the solenoids in original tranny put back in still will not shift into 3rd and service 4wd light is back on what am I missing

Are you getting any codes? How many miles?

No codes 167,00 miles

What is the difference between the 04 and 06 that will not let it shift

Have you tried putting the shift lever in 1, then 2, then see if it will shift manually into 3, 4?

Tranny from 06 got nothing at 04 tranny shifts ok 1 and 2 drops out in 3 not slipping just will not go into 3 rd