I just put in my new engine and rebuilt tranny in my 69 camaro. Before I started the engine, I was able to put the car in neutral and push it back and forth, after having started the engine for the first time, I can push the car forward in neutral but it locks up when I try to push it back, when the car is off. Any ideas why I can't push it backwards now?

oh and it is a TH-350, and I only put 8 quarts of tranny fluid in it so far

push harder graemlins/thumbsup.gif

Is the linkage adjusted right?

Is the e-brake on?