shifting problems need help please

i have a 95 chevy blazer lt with the 4.3 vortech code w...my problem is it shifts fine in 1st and 2nd but will not shift to drive....my ses light is on but i 45 miles from the closest parts store that i can get it scanned at, plus all of the hills....is there some things i can check...and what are your thoughts on this?

thanks in advanced

Need the codes buddy, need the codes..

Yip, without the codes we can't do anything.