HPA uses OEM style rod ends where the back side is enclosed and the bolt side is booted.
http://hpashop.com/Replacement-Joint...ment-Joint.htm
The black part is a seal/boot.
But what you're doing is fine as long as the boots fit snug against bolts/reducers.
Also, as long as the end link is the correct length, or can be adjusted to the correct length, it will work for either RWD or AWD applications.