Do yourself (and us!!!!) a huge favor and download a FACTORY service manual
Here's the updated page:
http://www.forabodiesonly.com/mopar/showthread.php?t=244981
Some of the links in the thread that were posted by Oklacarcollecto are out of date
I think the closest one is for 69 but no difference in 68
If your front suspension has not been touched in the last 20 years, you should just replace "everything"
Here's some good tech on part no's
http://www.bigblockdart.com/techpages/techindex.shtml