Ok I finally got the new tranny in and everything is back together and working great, but I seem to have a problem with the 4 low. The 2 hi works, and the 4 hi works, but when I push the button for the 4 low it flashes for a bit and then goes back in to 4 hi. any ideas on this.

 

Couple of questions, what year is your truck and what 4x4 system does it have, vacuum or electronic. Have you tried moving the truck slowly while engaging 4lo. It's possible sitting stationary that the gears are binding up.

 

This may sound like a dumb point to add, but is your truck in neutral when you try to shift into 4Lo? It has to be in 4Lo either rolling below 3MPH or stopped for the 4Lo to engage

 

The truck is a 97 S10 Blazer, and is 3 button 4X4.

 

Are you doing this when attempting the 4LO shift?