If you ordered a Cardone, it should be p/n# 54-71108. What is the code on your old booster (should be a "T3")?
Because 73-74 (assuming by your screename) are all that use the T3 rod, they might have used a more common core to build the new unit with. If the rod is long enough, you may be able to pick up a new yoke at the local hardware store. If you are trying to keep it original, you may have to R & R your unit.
Post the rod code, I'll help where I can.