i pulled out the front cross member when i swapped in a new tranny. and now the car pulls to the left on takeoff, but on cruising speed (40-50mph) it doesn't pull. is this an alignment problem?

 

Yes. The subframe is probably spreading/flexing. Take it to a body shop and have them check specs and fabricate a new brace if the old one won't fit.

The problem is more severe on takeoff b/c the engine needs to overcome the inertia/friction of the sitting car and is torquing against this. Rolling car has momentum and the forces aren't as great.