Chevy 400 tranny issue?

I bought a tranny th 400 ...it was working in the truck i was told. around 1971-1975 anyway i put it in a 1985 iroc..Its not shifting into drive ,it only has 1st and second. I noticed we put a rubber line for the vaccum to the carburator.Would that be collapsing and making it not shift into drive? What else could be wrong? I need help

yes make sure the line is not collapsing and also check your shift linkage. if you did not replace it try out.

you do need to run a hard line, it will not shift correctly if the line is getting sucked into itself you can use a little piece of rubberline to the ends but try to keep them short.. also did you change the filter before running it?

sounds like vacuum advance, or yeah the little tube. Also just because the tranny was working in the old truck, does not mean it was working properly.