Just changed transmission and when i started car it did not switch into gear when i moved shifter. Even in park it was at a free roll. Why isn’t transmission engaged?
Sounds like you may have not hooked up the shifter or some of the linkage correctly. That would be the first thing to check. Then check the rest of your installation. Did you connect the gear selector switch? Might not be a bad idea to check the fuses just in case. Fuse #47(shifter fuse), #3, #49, #46 and #2 come to mind.