custom length 8.75 axle questions-- need help!!!!

hey there guys! I am starting to build my 68 barracuda and i got a shortened rear-end, the overall measurement is 44-1/8th that is housing flange to housing flange.. outside measurement but while looking on DR DIFF for my axles they only allow you to select 45" thats the lowest you can go... so what am i missing or do i need to search else where? what size should i be looking for? mind you its an 8.75 with 489 case 3.23 suregrip cone... this is also my first build, im 26 and learning as i go! thanks for the advice and tips in advance!
Call Dr Diff he will be able to help you ,he is a great guy:thumbsup: