Which model locking hubbing do i need?

[87Ranger4wd]

I want to do the conversion to locking hubs on my 99' Ranger sport 4x4. I found a site that lists the AVM and Rugged Ridge hubs. I cant tell which one i actually need, their is a price difference and one mentions a 44spline count. Here is the link;

<http://www.autopartswarehouse.com/details/QQFordQQRangerQQRugged_RidgeQQLocking_HubQQ19992001QQ15001-dot-7.html>

It lists a part #15001.7 & 12667.01, not sure which i should order. Any help would be great