Bob...the F41 suspension rear swaybar was not available early in the model year. It made its debut sometime in the spring of 1970......as for the welded brackets, they were only installed if this option was chosen. Also, this option was not an "L78 only item"...it could be ordered on small block SS models as well.
So, what is the build date of your car?...if it is an early car then don't worry. Here is a link to the Nova Resource site it gives a little more info:
http://www.novaresource.org/rpo_F41.htm
wilma