the 4+1 is not and OD box. 5th is 1:1 and 1st is very deep (or can be-- they range from 2.22 to 3.76)
the one i did was 3.19 and i ran a 2.76 rear gear
*there is some combo of gearing that nets you a .86 or something 4th and still retains the 1:1 5th though.