First off, I am new to bike mechanics. I have a 1999 Diamondback Wildwood with what I believe to have OE. Bikepedia lists the bottom bracket as a YST BB 974, 122.5mm spindle (see pic). Could someone please tell me exactly what tool I need to remove it? Don't know why this is so confusing to me but I would appreciate any help.

It looks like it will take the same 20-spline tools used for most all square taper cartridge BBs

Park BBT-22 or BBT-32

Shimano TL-UN74-S or TL-6028 should fit, too

New to BB removal? https://www.parktool.com/blog/repair-...ottom-brackets

Even with the 4 larger keyways? Or maybe that's not so unusual (?). And thankyou!

Well, maybe someone else reading this is familiar with a tool that specifically matches the exact notch pattern of that BB. Or, for that matter, why the wider notches even exist. But, it looks like each of the wide notches will accommodate two splines on each of the above tools.

When/if you buy the tool get the version made for oversize (ISIS) splined spindles. The tool is identical except for a larger ID to clear the larger diameter spindles. That way it will not only work for you now, but will still be usable if/when you have one of the newer BBs.

[QUOTE=desertdork;14184751]...it looks like each of the wide notches will accommodate two splines on each of the above tools.[/QUOTE
I thought that may be the case. And I guess I should have checked the Park Tools website before I came here. It seems they have all the info I may need. Thank you very much for your help!

Whatever you do, find a bolt that will thread into the spindle to hold the tool tightly in place, they strip really easily. Either a bolt or this- https://www.treefortbikes.com/#navbar...22343539___283

The proper threading is M8x1.0 and you need a bolt about 40 or 50 mm long. Be sure of the thread pitch as M8x1.25 is more common but won't work.