Rear bump stop (jounce bumper) replacements?
 

Looking to replace mine, but they have been missing since purchase so I have little reference for what stock was like. Searches for the part number (52087639) didn't give me any specs, but I did find stock replacements for $50 each.

Then there are these pulyurethane ones, promising work better and last longer. $30 each is still a little excessive, but beats $50 for stock by a long shot.

Anyone know if these are the same size as the originals? Essentially just height I guess, I don't imagine width will matter so much as long as it fits in the cup.

Is there a way to measure the idea height for a bump stop? I imagine you'd want them to start engaging shortly before your springs are fully compressed.

Finally, the most important question, any idea where I might find a red version of these? Most of my suspension polyurethane replacements have been red because that's what they had. May not be my favorite color, but may as well match if possible.