that will depend on what it came out of. truck motor had it in the oil pan ,drivers side .that pan will not work in a mustang with stock suspension and will have to be replaced with an early pan. the timing cover would have to be replaced with an earlier cover that has provisions for a dip stick.
if it is from a car it should still be in the timing cover,passenger side right behind the ballancer .there will be a 3/16 hole that passes through the timing cover into the front of the oil pan. the dipstick and tube just pushes in and the tube bolts to the head at the top of the tube.