[/quote] Well, it appears out of the three holes the only vent is near the differential case. The end holes are for grease- fill cavity with grease until it escapes the hole. [/quote]
Perhaps the not-found (not drilled?) holes in my rear axle are the reason for grease on the brake shoes from over-enthusiastic use of the grease gun.

Re springs: Are you sure that yours are the right ones for a 2-seater? IMHO the number of leaves speaks for a 4-seater but I can be wrong.
Frank