/6 and SB 904 tailshaft the same? Driveshaft swap question

I pulled an 8 3/4 from a 71 swinger with slant six and 904. Im putting the 8 3/4 in another 71 swinger to replace the 7 1/4 that is in it. The second car is a 318/904 car. Will the driveshaft from the slant car be the correct length? Im thinking it should work.