A Body 8.75 housing/axles dont match

My Moser axels are 28 inches.

thats what mancinni sells to... so if my math is right on a factory housing of 52 5/8" or 52.625 - 1.5" (for the center space) = 51.125 or 51 1/8 then divide by 2 for both axles and u get 25.5". now this number would be from the housing flange on the axle. so a total axle length would be 27 11/16 as previously stated.
so wouldn't 28" axles be to long?