Not trying to be mean, but, It's quite weak actually, especially for the thickness of material used.
No 3D shape and right angle bends without any gussets or triangulation, There is pretty low torsional stiffness and bending in the transverse direction on the car would be pretty easy. These cars are basically trying to twist the car at the center of the transmission tunnel because that crossmember taking the load to hold the car up.
Compound that with only welding at the ends to what is essentially just sheet metal, that area is going to be highly stressed and bend easily.
The crossmember I used in my case is the way I would have designed my own if it wasn't available, basically 3 pieces together making a "c" type cross-section like the original, truck frames, etc. It's overlapped for a signifigant part into what is left of the original crossmember, and can be welded in place there.
You could use something like 1/4x1 flat stock on each end and lap over both ends and blunt the corners a bit and then it would be very strong.