You want a broadleaf weed control product for dandelions but you may have trouble finding it without fertilizer and you said you just fed the long with food and crabgrass killer? I would stick to the spray.
Exactly. I don't know of any granulated product other than the stuff like Scotts Turf Builder
Plus. Mostly fertilizer, with just a little bit of 2,4-D.
Read labels carefully. Some of the spray (don't know about Ortho) only has about 1/2 of 1% 2,4-D. Others have a higher concentration.
Your best bet - if available - is to get to a farm store, or an actual agricultural supplier. They sell the real stuff. My brother manages a large farmland cooperative. I can get 2,4-D from him that is much cheaper, and much stronger, than anything available in the "city stores."
Just be very careful of "drift."