I'm looking for an A body drive shaft to go with a 8 1/4 rear end

So I just bought a 8 1/4 rear end for my 69 dart, I have a 904 automatic trans and was looking for a drive shaft to work with the new rear end. I have two drive shafts that will work with a 7 1/4 but I think they are going to be to long by about 1.6 " . Any thought or options ? Thanks