i have a 99 blazer lt with the 4button 4wd....my tccm computer is bad and i can get a tccm for a 3button blazer ls same year....now can i use this computer and have it work the same minus having the auto 4wd option or do i have to use one from another 4button system??? im really missing my 4wd

 

No. The two TCCMs are completely different and cannot be interchanged.