Anyone ever install replacement rear shock crossmember from ART?

[69RTSEV88]

I need to install the replacement rear shock crossmember in my '69,  the original was completely removed before I got the car (damaged from air shock use).  The replacement part from Auto Rust Tech. looks very strong, but comes up short about 1/4" on both sides of the frame rails.  Is this normally how they are?  Do I have to weld in some spacer plates to close up the gaps?

[AutoRust]

Just sent you a PM

Dave