Double Hump Crossmember Help ~ I confused.

[Demon of Dreams]

I was at a boneyard today and was looking for the double hump....

however... I don't know what the hell I'm looking for.

Basically I have a few different options.

One: Crossmember with no lateral bars.
Two: Crossmember with lateral bars.

Now... even the crossmembers that have the lateral bars are different... some have a lot of holes, some only have a few.

Some have 2 mounts and some have 1...

the one I had them set aside for me later measures 33.5 tip to tip at the laterals, and 33 even tip to tip on the main crossmember piece, and 5.5" from bottom of crossmember to the highest point of the lateral bar...

I've got a 350/TH350 2WD ...

what exactly am I looking for to do this??