8&3/4 axle fitment problem

I superglued a thin flat paint stirring stick on either adjuster on the sides & got 8" across between the two & the depth of the thrust block in from the adjuster(s) is 3&3/8 on each side so 8 - (3&3/8 x2) = 8- 6&3/4 for a thrust block width of 1&1/4" but the OE SBP 8&3/4 axles would not go in either then it hit me that I drove the thick grease seals in 1&1/16 on each side, ( I drove em in till the outer side was just past the point where the dia narrows slightly, a slight lip) & the light bulb came on & I'm thinking that I did not drive em in far enough & that is where the interference is, further strengthened by the fact that even the SBP axles would not go in either. what do you guys think? RR