Spindle help

[nadodave]

Hello:

Still plugging away on my '63 Panel. A number of years ago I bought and installed what I "was told" was a '71 front suspension including disc brakes. It installed pretty easily. More recently, I bought a McGaughy's 2.5" drop spindle kit. The suspension shop tried to install it for me, but discovered that the ball joints do not work with the new spindles. They found a ball joint that works for the upper control arm, but the lower control arm has very large hole for the ball joint that they cannot find a joint to fit. In an effort to figure out what is going on, I got the casting number off the existing spindle (see the pictures), but haven't been able to google any info. It looks to me like the number is RH 23988482, but it could be 23388482 or 23888482. Any idea what vehicle this spindle is from? Thanks in advance