i just installed a small block 400 in my 84 vette. i also installed my 700r4 which had been rebuilt about 1 year ago. we fired up the vette today (not the first time since install) and it was sitting in park. all of a sudden it was like it was in drive and started smoking and lurching forward like it was in drive. it then made a horrible noise and now when you try to start it up, it is like it's in drive but has no reverse and will not pull forward or back. it just feels like it's engaged. what could this be and will a 350 or 400 tranny just bolt in?
thanks

 

Maybe didn't get the torque converter engaged on the pump during installation? The TC has a biiiig slot in the end of the splined hub that slides over the input shaft, purpose is to drive the pump.

It's easy to miss during installation, makes sliding the trans all the way up to the bellhousing a bear but will still go together...and fry the trans shortly after startup.