how much transmission fluid needed in a 94 suburban

Take it to a shop. If you add too much your Sol. Same if too little.

l assume you mean if you drain the pan.most full size take 8 quarts. if you drain the converter almost 16

If you have the 700R4 trans, and your just servicing it with a new filter and fluid, you need about 5 quarts of fluid, start and check it at 4 quarts to avoid any over filling, if the trans is new and dry, about 11 quarts.