i have a 11 ram 1500 crew cab with hemi 2wd and has the facotry hitch assembley which is hidden thru the bank bumper.it looks like all u do is buy a ball and install into hitch thru rear bumper.my question is how uch is that hitch assembley good for it aslo has the 4 and 7 pin plugs too.i want to tow a 99 viper gts with it.is it safe?