Subframe connectors for a driver/cruiser, necessary to weld to floor?

I intend to install bolt-in subframe connectors on my 69 Dart but I am unclear where to get them as it seems there are plenty offer for 70 and up years but not so much for 69. Does the 69 have a 108" WB? I was looking at Mopar Performance or Hotchkiss.

Many have commented "You don't need them" regarding these. How is it that we don't apply this axiom to any other changes we chose to make on everything else on the car?
Upgraded brakes, tires, suspension, electronics, cooling, power and other "not needed" stuff we don't seem to have trouble dumping money into.

We "unnecessarily" changed the steering on my son's 65 Nova to an aftermarket power rack and pinion unit and added subframe connectors. That converted a 5-turn LTL poorly handling death trap to a slot car.