Will the pinion from a VL 3.45 gear set fit the tailshaft flange in my EA?

Currently 2.92:1 if it matters.

Also, no flamage, does 75 series refer to 25 spline setup, 78 series; 28 spline axle setup?

i think the spline on the VL will fit alot of people look for the vl turbo gears because some of them came with 78 series and no the 75/78 gear does not refert to the sline drive on the axel. it is more to do with the center itself.