742 8-3/4 Sure Grip Rear

I ended up trimming of about a 1/4 inch to get them installed
How did you determine that ?
I would call Moser and ask them what length the axles should be with that width housing and remeasure yours .8 3/4" axle shaft lengths (measured from the tip of the splined end to the outside of the flange)
Stock axle length A body '66-'72= 27 11/16"
8 3/4" Housing widths, flange to flange
A-BODY 66-'72= 52 5/8” (If correct) I cut axles wrong base on false Data once.
Based on your info. your axles should be 24.731" long
Don't trust me though. I based this on info from this Post.
I did not know there were 2 set of splines?
Also, I'm no expert so maybe someone will chime in. Just trying to help.

An accurate 8 3/4" rear axle width list