trans..prob?

I worked on gettin the motor goin in my 79 formula ...which has a 400 bb..sounds great purrsss like a tiger....but when I put it in gear nothin happened..yes yes i know I dont really know much about about cars...so could u guys throw some ideas at me why it aint movin...I hope the tranny aint shot....cause I dont think the tranny in my 305 will work will it? :smokin: any help eould be great thanks