Hate to spoil the party but you have the right design on your vehicle currently..The one you ordered is the one that you should see that bolts to the upper 'A' frame..you'll see it..As I stated...you currently have the right 'style' on your vehicle..I don't normally look at the clearance after mounting one but I personally wouldn't loose any sleep over it..You certainly have more important things on your menu...Jerry

 

You haven't spoiled anything Jerry because you're wrong. The pictures below show the upper bump stop you're referring to. GM p/n 15590236.
Notice the difference??

 

you'll see who is wrong when you get the part.....I've done hundreds of these things...My guess is you've done a few less than I.....What you ordered goes on the upper 'A' frame...not where you've installed your bump stop...you have the correct one...The Z thing you spoke of is a ZR2 Blazer and actually your vehicle or the ZR2 can utilize that same 'bump' stop..Good luck..I tried...

 

Anyone have a diagram for installation or any other help for installation?. A quick look today and I saw what looks like @RedSledge most recent part pics. Does each side of the front end use 2 bump stops, an upper and a lower?

 

I DID get the parts - late this afternoon. And guess what, you're still wrong. The attached pic proves it. And by the way, installing the wrong part "hundreds" of times doesn't make anyone an expert. I prefer to research a problem and gather evidence. That's why I've posted pictures and part numbers all along. You, on the other hand, charged onto the thread with wild claims and rhetoric, and presented not one shred of evidence to back up anything you said.

And, do you actually think I made up that spec about the Z high ride option? It's written that way on the Summit Racing site, which you would have known if you'd actually read the post.
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PS The part numbers shown on the pic are listed right on the boxes for the lower, and on the box and the pull tag for the upper.

 

@RedSledge I checked out my truck and I have the round mounting base too but the rubber is long gone. Seems like they redesigned the part to move the contact point outward. The uppers are essentially untouched and looks like they have never been impacted.

Did you get the new ones mounted, is there a size difference? I want to replace mine and it looks tight but accessible, but I watched one video where the guy took half the suspension apart to do it.

 

Not arguing with anyone about which style fits, but on all 5 S-series trucks I've owned ('96-'04) over the years the factory installed front bump-stops are all round . It's also entirely possible that BOTH parts are the correct part. Where they sit on the frame, it appears that either a round or a square bump-stop could work.

As well, one thing to keep in mind is when evaluating how these affect the ride quality is that it's quite probable that the factory suspension is sagging a bit after 20+ years. Unless you've adjusted or replaced suspension components to put your ride height back to factory specs and height, you'll be closer to touching the bump-stops with any suspension flex.

Also the material will affect the flex of the bump-stop. If the yellow bump-stop you had is made from urethane, it will be much stiffer than a rubber bump-stop like the square one shown.

 

I may not be as computer savvy as you, Red Sludge but as El Beautor states-he is correct...Yours appears to be about an 2000/01...a 4wd...The bump stop you said is correct for yours IS INCORRECT...It is for an S10, 4wd from 83 to 87... Is NOT the one for your 4wd (2000 ish)...Check with your local Chevrolet dealer and you will see...As I did this morning...I am going to chime out of this conversation and leave it to your 'expertise as I perform 100's of jobs incorrect...and I have a full menu of Blazers on my list to screw up...Not saying that you can't install a #88912477 on your vehicle but again...Spelling it out for you: It is incorrect...The one you already have on it is correct...OUT....

 

The bump stop job is done and the ACDelco parts fits perfectly. In fact, they fit much better than those crummy Chinese imitations - which I had to put in a vise to bend out the index tab before they would even engage in the hole. But not the Delco part! No bending or modification required. The index tab fits into the index hole without issue. And I'm really REALLY thrilled at the improvement in the ride now that I've got full front suspension travel. With the Chinese stops, I could feel it bottoming out on mild pavement irregularities.
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To the member who said these stop were actually made for a model in the 80's, I noted on the ACDelco box that the graphic design and logo was copyrighted in 1995 (just in time for our 2nd gen trucks!). That's not to say these can't be made to fit the earlier trucks too, I frankly don't know, but that 90's copyright makes that idea a little suspect.
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And to the member who suggested my truck might be sagging and that's why there was so little travel with the Chinese stops - I guess you didn't see the post with the pic of the right side sitting perfectly level and including measurements. I'm pretty sure someone would have said something if the truck was leaning, sagging, or otherwise didn't look level, or the measurements didn't jive.

INSTALLATION -
I've included some self-explanatory pics you can use for reference. But the job goes something like this:

1. Jack the truck up and put jack stands under the frame. Remove the front wheels.
2. Put your jack under the lower ball joint and CAREFULLY raise the suspension just enough to provide some clearance under the upper control arm, but not enough to take the weight off the jack stand. At best, it's still going to be tight getting your fingers and a wrench in there.
3. Remove the nut from the Chinese bump stop and discard it. Mine required a 17mm wrench. But knowing the Chinese, yours could be anything.
4. The Delco part has a standard 3/8-16 thread, but they include one of those 'interference fit' lock nuts that are so difficult to turn. Considering the tight quarters and the length of the stud, I opted for a 3/8-16 elastic stop nut (ESN) instead. They're just as secure, and much easier to work with.
5. To get the nut started, slip it into place over the hole with your finger pressing on its top. Then, with your other hand, guide the stud up into the hole and turn the whole bump stop into the nut while holding the nut level.
6. Tighten the nut with a 9/16 ratcheting box wrench if you have one, or an ordinary box wrench if you don't. Tighten it good ~ 30 ft. lb.
7. Lower the jack from under the ball joint and place it under the frame. Install the wheel.
8. Remove jack stand and lower unit to floor.
9. Done!

For the pics, I'm starting with the one that shows the final result - 'cause it warms my heart' - The annotated in-progress pics follow.

 

Congrats. I'm glad the part you found worked, and you're happy with how your truck drives now.