Will the rear axle fit?

Does anyone know if a 8 and 3/4 rear axle from a 1968 B- body would fit in a 1974 dodge dart sport originally with a 8 and 1/4 rear axle (A- body)? The 8 and 3/4 axle is a 3.23 sure grip and the 8 and 1/4 axle is a 2.76 peg leg. Would I be able to just swap out the two? Are the measurements the same?
Thanks, Kameron