I just purchased a 2001 svt cobra convertible with IRS rear end and rear differential is seeping/dripping a bit when parked. I want to top it off to make sure its not low since I have no idea how long it has been dripping. Will I be able to stick my finger in the fill hole and touch fluid when it is full.? If not is I assume no way to tell when full other than to drain completely and start from scratch. and not much room back there to remove rear cover. thanks, for any help. Jeff