[dana44]

Welcome to the forum. If the mounts have been changed, it may have altered the throw on the shifter itself. Check that the transmission is actually shifting far enough to go into gear, it may not be actually clicking into reverse gear. It happens. Check the manual to reset the adjustment, not sure if it is neutral that is the setting point or not, but usuallyl is.

 

[chuzz]

I agree with Dana. Check your linkage and make sure it's not in a bind. If it was working before you changed the rear motor mounts, then you know it has to be related to something you did.