This would have been better if you'd added it to your distributor thread.
http://www.forabodiesonly.com/mopar/showthread.php?t=240137
1--The "thing" "down there" is the distributor bushing. That one looks like it needs replaced
2--You are missing the distributor intermediate shaft, which I already posted a photo of on the other thread. This is a one piece shaft with a gear that mates with the cam gear and has a drive slot on top to drive the distributor. The shaft goes down through that bushing and engages the oil pump
It's time you started reading a shop manual. Down load one or three:
70-71 Mopar Parts
[ame="http://www.abodyjoe.com/pictures/Misc.%20car%20info/1970-71MoparParts.pdf"]http://www.abodyjoe.com/pictures/Misc.%20car%20info/1970-71MoparParts.pdf[/ame]
72 Service Manual
[ame]http://www.abodyjoe.com/pictures/Misc.%20car%20info/1972%20Plymouth%20Chassis%20Serv%20Man.pdf[/ame]
69 Dodge Serv. Manual
[ame]http://www.abodyjoe.com/pictures/Misc.%20car%20info/69%20dodge%20service%20manual.pdf[/ame]
70 Dart Challenger manual
[ame]http://www.abodyjoe.com/pictures/Misc.%20car%20info/70%20Dart%20Challenger%20Serv%20Man1.pdf[/ame]
71 Dodge Body Manual
[ame]http://www.abodyjoe.com/pictures/Misc.%20car%20info/71DodgeBodyManual.pdf[/ame]
65 Plymouth Manual
[ame]https://www.dropbox.com/s/upks33txhbe9tjw/1965%20Plymouth%20Service%20Manual.pdf[/ame]
and from MyMopar, you can download a 66 and a 70 manual, as well as a wealth of info
http://www.mymopar.com/index.php?pid=31