The knobs are being reproduced by Rudy's KF Parts in Ramona, CA
Rudy's 2006 catalog lists it as "51-53 Kaiser Shift lever Knob for std. transmission", part number 207989. The price at that time was $22 plus 8% shipping and handling. That was 2 years ago so I'd recommend calling as prices may have changed.
Rudy's number is 1-760-789-3608. He is not known for returning calls so if you leave a message and don't hear back within a day or so, call again. His stuff is nice and I've been real happy with it. I bought a shift knob for my Henry J from him and it's great. I will say be sure you clean all the old glue/remnants etc out of the grooves on the lever and lube it with Gojo or some other non-residual lubricant to aid in pressing the new one on. Take your time, be patient and it will go on and stay and you'll be very happy with it.
I also put one on my '51 Kaiser years ago. Here's a picture so you can see what it looks like.
Good luck!
