The more variable change will be you. It's been over 20 years. The D3 is the closest in shape. But you really need to find the best match to who you are today. The Titleist Thursday program if you can find one within driving distance is both excellent with knowledgeable fitters and fitting tools for the right price ($0.00). A good fitter will match head, loft, and shaft to you.

I held on to my 975 for about 20 years as well. Loved that club. But Tech has left it in the wake. Currently gaming the 915 D3 model and the difference is night and day. I like the smaller head profile of the D-3 vs other models of the same vintage. Made the transition easier visually. The new club provides a little improvement on the distance but It is soooo much more forgiving. Hope that helps.

Golf club technology has come a very long way since the late 90s, the reality is that there are no Titleist drivers that are similar to the 975D (by the way, it was the first Titleist driver I ever bought). Looking at all of the other current drivers on the market and the answer is the same. If you can find one, go to a demo day and try some of the various brand offerings that are currently available.
If you are set on getting another Titleist driver, then look for a Titleist Thursday event in your area and schedule a fitting, it's free. Going through the fitting process with a Titleist fitter ensures you get the correct head/shaft combo for your swing. If you can't find a Titleist Thursday event, then find a qualified Titleist fitter and schedule a fitting. It won't be free, but a lot of fitters will apply the fitting cost to the cost of the club when you order through them.

Well that is one of the best drivers ever made. I miss mine.

Short answer: nothing is close. give the TS line a try and see what works.

I have been gaming the 917 D2 for about 3 years now. I have tried several different drivers but simply hit this one the best overall. Good luck !

Still got the 910D3. Love the head shape. Small.

975 was my favorite driver of all time, still have it the garage and recently put new grip on it. I take it out on the range from time to time and I can tell you I hit the 975 straight as a string, but my TS3 is considerably longer; no track man on the range, but I would guess 20 yards or more. Do yourself a favor, find a Titleist Thursday, and try the newer drivers. I have always admired how Titleist keeps the club appearance very classic from address. I think you will be surprised how quickly you will be comfortable with the current club heads. Happy hunting and kudos for gaming that driver for so long!

I've been playing with a 975D myself since 2004. I can't stand the newer gigantic club heads and I've always hit my 975D straight as an arrow. This year I'm seriously getting back into golf for the first time really since my college years ('01-'05) as I ruptured my Achilles playing volleyball in November and essentially won't be able to play anything but golf until the fall.
I just picked up a 910D3 a couple weeks ago and am loving it so far. My only problem is that mine came with the red weight and it has been causing some slice action and that is something that I never got with my old 475D. Aside from that though, the 910D3 has most certainly been the most comfortable feeling and similar "modern" driver that I have come across so far to my old trusty 475D. I'd highly recommend giving that a shot, you should be able to find a used one for very cheap that will be in very good condition. Shoot me a PM if you'd have any questions on where to look.
Also if anyone reading this happens to know where I'd be able to find some of the other weight options (especially whichever weight sets up best for someone with a draw ball flight) and would be able to help point me in the right direction that would be greatly appreciated!!!

For your 910 D3, have you tried adjusting the hosel? In looking at the chart (you can find a link under Clubs - Drivers) resetting the settings up and left (for RH golfers) will tend to shape the shot more to a draw. Increasing the loft from A1 to the next setting up will effectively move the face from slightly open to closed. Surefit settings for drivers are unchanged from 910 through the current TS models. As well as shaft interchangeability. The shaft might also be too stiff for your swing. A lighter flex may allow the head to close better. But that's up to you and a fitter to decide, if the hosel settings don't improve your fade.

The weights, besides being incredibly rare for a 10 year old driver, are primarily to adjust swing weight, not adjust face closure at impact. The preferred tool to use with the hosel screw in the head is from Titleist. It also clicks when the tension is tight enough, but is otherwise a standard Torx fitting. Other vendor tools may also be the same size.

Thank you so much for the insight and tips, I really appreciate it!!! I was actually thinking of adjusting the hosel yesterday, I just don't have the Titleist Surefit Torque Wrench yet (I ordered one last night!).
My 910D3 is currently set at A2. Based on the Performance Fitting Guide Chart I think I am going to give D3 and maybe A3 a try and see if that will help eliminate my slice action.
Thanks again Don!!!

Thank you for the insight and tips, I really appreciate it!!! Yesterday I was actually thinking of adjusting the hosel, I just don't have the Titleist Surefit Torque Wrench yet (I ordered one last night!)
My 910D3 is currently set at A2. Based on the Performance Fitting Guide chart I think I'm going to try D3 and maybe A3 to see if that will help eliminate my slice action.
I do have a pretty slow swing speed as well, if the loft adjustment doesn't help and once I feel closer to 100% with my swing in the next month or so with my Achilles recovery at that point I would strongly consider a lighter flex shaft. If I can find a Titleist fitter in my area I would jump at the chance!
Thanks again Don!!!