Manual Steering Box Seals

I bought my 20:1 worm gear from a member on SL6.org for a heck of a deal but Firm Feel sells them.

The seals I mentioned are for a "small sector shaft" box, I believe '72 and older.
The worm gear seal I believe is the same for all years, but the sector shaft gets bigger after '72, so it requires a different seal.

Someone correct me if I'm wrong...