I recently replaced the trunk floor and floor support on my 70 Satellite conv. The floor was so bad that the support was gone. I noticed that the supports are different between 69 an 70. The 69 version has two sloped pieces welded to them, probably for centering the gas tank. 70 doesn't have them. there appears to be two nuts welded to them that something bolts to, but I don't know what. The repos are the 69 style and that is what I installed. Should I just cut the pieces off ?

Does it appear that at some time there was something threaded into those now missing nuts on those support brackets? If it doesn't appear those nuts had anything threaded into them, I'm not sure I would be concerned. There may have been something optional that required those nut to be welded into the braces. If the nuts were not used on your car, I wouldn't worry, unless your doing one of those paint dot restorations.

Wild guess?
Maybe the difference is for the gas tank straps? Does your 70 tank straps have a bolt where the nuts were welded into the bracing?
If I remember correctly, the 70 tanks had more vent lines then the 69s had, maybe Chrysler changed the tank strap mounting method because of the extra vents. Gene