Doug - I think your are talking about the throttle linkage bosses (there are 2 depending on the year of your block) as shown in a couple of screenshots of pictures in this
Throttle linkage thread.
IIRC, both are machine screw threaded for mounting the throttle linkage pivot post, with the position dependent on what vehicle the engines were installed in. I also seem to recall that one or both were threaded all the way into the block coolant passage and the throttle pivot and screw to fill the unused mount hole needs to have sealant on the threads to prevent leakage.
Post a pic of yours and we can chat further if needed.
