A B-body K-member is only a little heavier than the 35lb A-body K-member. It's hard to get much lighter than that.

The LCA pin tubes were underwelded from the factory. This is a 73-76 A-body K that I took apart to straighten and add reinforcements to the inside. You can't get to this area without cutting the K-member open (a small area, perhaps 2" x 2" would suffice).