I followed FAQs

https://www.brickboard.com/FAQ/700-900/EngineSealsBeltsVent.htm#VolvoCamTool

to insert my Viton/gray crankshaft oil seal. On my 1988 240 DL N/A, a 2" wide ABS pipe with cap, like this

https://www.lowes.com/pd/NIBCO-2-in-dia-ABS-Cleanout-Adapter-Fitting/1000221933

and rubber hammer (mallet?) worked after 30 minutes.

On the 1980 DL N/A, after about 1-1.5 hours, I got the seal aligned only to the outer lip; per the FAQs, I took several breaks to ensure that the lip didn't invert (or spring twist?).

However, on the inside surface of the crankshaft oil seal housing, there's a tapering area and the tip of the original seal was mounted at the base of the tapering, about 5 mm inside the lip. I couldn't get the seal in any further past the tapered area.

I then used the FAQ's suggestion of using 22 mm crankshaft bolt and drilled a hole in the center of the ABS end cap, per the FAQs. It was very easy and I was able to get half of the crankshaft oil seal flush with the flat part of the inner lip and past the tapering part. However, it's misaligned on about the other side. I removed the ABS cap/22 mm bolt and tried hitting just the side that sticks out, to no avail. I'm stopping for the evening and would like advice on how to align this.