Mr Goodwrench, You forced me to break out the trusty dial calipers. Yes, the three holes do go all the way through. First diamiters of , the three steps----- Bottom 1.370 middle----1.445 top----- 1.490 Measurement from bottom of sleeve to first step---2.950 middle---1.100 and top 1.17 Hole diamiters measure .210 13 holes in the bottom sleeve ( .450 from center of hole to bottom edge of sleeve) holes at top of bottom "section" are 2.650 from center of hole to botttom of sleeve. 3.820 from bottom of sleeve to center of holes in middle section. 4.450 from center of top holes to bottom of sleeeve. Using calipers instead of original tape measure the sleeve from bottom of flange to bottom of sleeve is 5.150 Flange thickness .440 Inside diamiter of sleeve 1.250