telling tranny mods by driving

first....not originally a mopar guy...i'm new to them....

are there any obvious ways to tell to what level, if any, a 727 has been modified....besides, obviously, the firmness of the shifts.....

i've never had a car that wouldn't, but apparently there are stock trannies that will not let you downshift to first above a certain speed or sutomatically shift out of first anyway....

guess i'm getting the notion from kits that claim "allows you to hold in first to any rpm" and "can downshift to first at any speed"