Just to add a bit to Duane's tips, I had good luck using a clutch alignment tool to get those splines lined up.

I used a plastic one like IPD shows at the bottom of page 23 in the latest catalog. Most places like NAPA have them for about $5.00. You want one with 22 splines (the 23 spline in ipd is a typo).

I cut off the ringed end and epoxied in a 10" piece of wooden dowel for a handle. A little pushing and wiggling and you're all set.

And it's easy to do it again under the car if you have to re-try. (Mine went in on the 2nd attempt.)
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Bruce Young,
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.