I'm replacing my stock worn out birf with a newfield and think i might have got the wrong part. The input splines to the newfield seam smaller than the axle. I haven't seperated the axle and birf because I'm afraid to break the old birf if the newfield is the wrong one. I'm taking my cruiser on a 1400 mile round trip to Vegas starting wednesday. Does the end of the FJ80m axle step down at the birf joint??? ???