Vintage MTB, mounting new v brakes I'm installing deore v brakes on a 1988 Bridgestone mb2.
The front brakes installed fine.
On the rear, the pin on the v brakes that is inserted into the frame to set spring tension does not align with the hole in the frame. It's misaligned by a mm or two.
This is my first v brake setup, could be missing something obvious.
I definitely have rear brakes. Also tried installing a front brake in the rear, with the same misalignment.
Not sure if this is an issue with standards that have changed over the years? Strange that the front pins insert perfectly.
I find the v-brake on the front fork, which often times has just one hole for the spring pin, is a smoother install. Idk why.  There is no difference in "front" or "rear" v-brakes except the direction of the pads.

Typically at the rear, the frame's tabs where the brake bosses are threaded or brazed on will have three holes per side drilled in them from which to choose the insertion of the brake arm's spring pin. Each arm's spring pin should be placed in the same relative hole (if the left spring's pin is in the middle hole, the right spring should also be in that side's middle hole).  Spring tension is highest when the upper most hole is used. Typically the middle hole is chosen. 

One way to ease getting the pin into the desired hole is loosen the brake pad's nut enough so the pad can be rotated parallel with the arm. In this position the whole side of the brake can freely rotate on its boss without the pad bumping into the seat stay.   This way allows easier access and placement of the spring pin into your desired hole.  This may be the crux of the problem. Is the brake pad blocking the movement of the arm before it's pin is sufficiently lined up with the hole?  

Park Tool has a great tutorial on installation of linear pull brakes.  V-brakes is a term coined by Shimano and is a linear pull brake system.