These red or black knobs are 1-5/8" in diameter, and have 3/8-24 (fine) female threads in a brass insert. They should fit most Morse and Teleflex controls with 3/8-24 threaded levers. The brass insert prevents plastic-on-metal thread wear, so the knobs don't get wobbly over time.
Note that at 1-5/8" diameter, these Teleflex knobs are larger than 1-3/8" Morse knobs.
When replacing the knobs on some older units, the outside of the knob might be a slightly different dimension, but the knob will have the same thread.

Although the Morse knobs (035232-001 Red; 035232-004/044 Black) are still available as of this writing (8/11/14) they are slated to be phased out, and after that you may not have any other choice but to use these larger Teleflex knobs for older Morse controls.