1963 Steering Disc Fastener - Rag Joint

[sombb]

Hello,

Working on my '63 Landau, replacing its ancient rag joint (rubber disc) coupler linking steering column to steering box. With the dash and instruments now removed from the car, easiest to leave the steering box in place and detach the steering column into the passenger cabin. One problem: fastening bolt securing disc to steering box is one I've not run into. Attached is a photo.

Can someone identify its type and head size. Definitely NOT Torx. Alternatives I've found via Google: Double Hex, Spline Drive. Other? I need to hunt a socket that will fit. Thanks.

 

[74 Harley]

It's a standard 12 point socket. If I remember correctly 1/2 inch.

 

[Frankie the Fink]

Unless that disc carcass is torn I'd try to keep it, or find an NOS version, nobody makes the correct 7-layer carcass anymore and the repros are pretty crummy rubber versions; I've dealt with this a lot on Corvettes. If the safety stop metal pins don't show wear the carcass may well be fine. This video is typical of the rubber that repro coupler vendors sell now; its flimsy and will transmit shcoks and sloppiness up the steering shaft and wear quickly - I can distort it with just thumb pressure.
Chiwanese junk:

 

[sombb]

Hi,

Getting the fasteners right is challenge enough. But a downgrade in the strength and durability of the rubber I didn’t realize. Just cuz I can make a change doesn’t mean I should. Thank you.

BTW, for the bolt, regular 12pt socket 7/16” did the trick.