68 fuel sending unit issue, need info

[littlehopper]

Fuel gauge never worked since I bought my C20 about 3 years ago. It took running out of gas 3 times to push enough to deal with it. Well that and a tank full of sediment clogging my fuel filter.
So I bought a tank at Carlisle and a sending unit from Summit(made by Keystone) Original unit has threaded stud for wire while replacement has a stud that looks like it would use a clip on connector.
Ok, I decide to try another supplier and go with the truck shop which is a Counter Part unit that also has a clip on stud.
Should it be threaded or clip on? Where can I get a clip on connector for one of the replacements?
Any help would be greatly appreciated.

Thank you, Joe