I have a Gary Fisher Mamba frame that I am going to do some updates to such as replacing the seized front fork. The frame originally had a threaded headset. I would like to convert it to threadless. The bearing fit right in the headtube and I did not have to use any tools to get them out.

Does anyone know what headset will work?

I think the bike is this model and year.
https://bikepedia.com/QuickBike/BikeS...amba&Type=bike

here is a pic of the headtube

Possibly this one?
https://www.pricepoint.com/detail/189...DL-Headset.htm

You have a standard pressed-in (non-intergrated) headset. While you removed the balls and retainer the cups are still in the frame and need to be pushed out.

Then you can fit any conventional (pressed-in) threadless headset of the right size, probably 1", since 1-1/8" forks were rare. Headset sizes are defined by the diameter of the steering column of the fork, so match your fork with a threadless one of the same size and buy the matching headset.

1-1/8" threaded headsets weren't that rare in older MTB frames. I had a 1993 Trek 7000 MTB that had a 1-1/8" threaded fork and corresponding headset. As you said, the OP needs to measure the actual OD of the current fork's steerer tube and buy a headset and new fork to match that diameter.

Wait a minute, if you can use a threadless headset for a frame that took a threaded headset, can you use a threaded headset for a frame that takes a threadless headset?

yes but you will need a matching threaded or threadless fork

The frame fit for the same size threaded and threadless headsets is the same. what;s different is the stuff for the top of the fork. Also note that if changing from a threaded to threadless headset and fork, you'll also need to switch the stem.

Rare in this context is a relative term. You're right, they weren't that rare, and there were even some 1-1/4 threaded systems out there, though these were rarer yet. In any case neither were nearly as common as 1" threaded forks.

Threaded fork is cut shorter than the height needed for clamping
a stem on a threadless fork,

Just look for another threaded headset, one of nicer quality, to be sure..
cheap headset was part of meeting that low price point.

a proper conversion will = the money you paid for the whole bike.

do you have tools to press in new head tube cups?

I agree with fietsbob, buying a new threaded headset or merely rebuilding the original will be far more worthwhile in the long run considering the expense of updating your bike to a threadless system. However, if you are set on adding a threadless setup instead, you will need a headset of the proper diameter, a fork to match that does not screw too much with the original geometry of the bike, and a threadless stem along with spacers. I suspect that finding a suspension fork with a 1" headtube will prove to be a bit of a hunt, but I have never looked myself and you may wish to stick with a rigid fork. Good Luck whatever your decision may be!

Cheers

I saw that it has cups that are pressed in. It is a 1 1/8 headset. The reason I am going threadless is because I want to update the fork. The suspension is an old junk post modern fork that has seized up. I am going to put a new fork on the bike. Thanks for all of your input. I will probably take the bike to a shop to have them remove the headset, and put on the crown race.