Does anyone know if the crossmembers are the same for a 4-speed and an automatic tranny on a 70 or are they different? Thanks in advance for any help.

THey are not the same .
the 4 speed has a bracket for the rear shifter mount.

Thanks for the info.

You only need a 4 speed crossmember if you are gonna run a stock shifter. A automatic crossmember will work fine if you are using a aftermarket shifter like Hurst.

Dave