'Sorry I missed this one. I think you have a mixture of 7005 and 6061. Extruded and drawn tubes will weld the same. When you look at the description of 6061 you will notice other numbers after it. the "T-6" part has to do with the hardness or "condition" of the material. other stuff after than has something to do with how the material was made. T651 is extruded bar I think (not fact checked)

Anyway, after sanding the surface of all your new, never painter or plated sample pieces, then cleaning with 3M scotchbrite 7447, then finally a solvent of isopro or acetone, buy some new 4043 "non -ebay" filler wire also cleaned with solvent (we don't know where you rod has been), you will strike an arc then do a short weld on one piece at a time. The 7005 will have a green glow or hue around the arc. The 6061 will be clear/white.

Aluminum tubing is sold in fractional sizes with the wall described in thousandths of an inch, (035", .049" etc).. Most online metal sellers don't know the difference between drawn and extruded and they certainly aren't going to know if they call it "16 gauge" and some 7005 bicycle tube manufacturers grind the surface so you can't tell if it's drawn. I mostly tell by crushing it in the vise then breaking it off. Drawn tube is tougher.

Easton hasn't made tubing for 10 years. The stamp/name means nothing to the fabricator.