E-Body 8:75 Axle Housing Differences

[Floyd]

Looking at two E-body axle housings today and noticed some differences between the two. Overall length and spring perch location are the same. Note the wider flaring of the axle tube where it meets the flange on the bottom one. The bottom one is the original out of my T/A and the original in my 71 is the same. Is the narrower flaring from a later model? Also, which vent style is correct for a 70?

Thanks!