I don't think GM ever made 3-leaf mono replacements but hope you are right nowadays!!
As for buying new mono's!
Nobody re-pop's mono's b/c they are double tapered!
A stock mono is 2.75" wide on each end and thin and 2.25" in the middle and thick and they have a bottom locating "tit" on them!
Leaf springs are 2.5" wide and the same thickness pretty-much along their length and have a bolt through them that locate's them both top and bottom.
The 3-leaf mono replacement springs are the same width as the mono's so fit fine except we have to trim the lips off the sides of the center pads. They have a countersunk headed 5/16" bolt so are smooth on top and locate w/ the bottom nut.
Here is the info that I've saved on this that's probably also in the sticky!
"Here's the information on these springs. They are made by S&G Enterprises, Inc. Their website is S&G Enterprises and the part # is 21-245. They are made in Mexico. This same part shows up on this website Triangle Spring as factory replacement springs. They don't list the details such as spring rate on either site though.
My JCW cat. is number 671J-02 and the spring number is 94UA2669X at $62.95 each.
If this cross references to one of the numbers you listed which should be the second one down.
More info on the JCW springs. According to the sticker on the springs I installed from Vette Brakes the JCW/Triangle and VB
springs both have the same PN (21-245).
I am going to assume they are the same spring given the PN and the fact my VB
springs were labeled "Triangle". This would make the JCW springs #130.
The curious thing is after the install my rear end is about an inch higher with the VB
springs than other who have used the JCW springs. (Yes, everything was tightened after it was on the ground)
Here is the thread with the info on my VB
Just trying to keep all the pertinent info in one thread.
St. Louis Spring = 1-314-533-2132, Mon-Fri 7:30-4:30. Per Mike P.
phone # 1800-521-0563 hope that helps let me know."
And I have JCW's 3-leaf mono replacements under my car except that I added the second and third leaf's to each side from my old '68 'Bird's broken multi's to better balance out my now about 525 pound front coil springs! She set's way high, just about right for a pair of L-60/14's in back. (Mine measure a modern 298/53-14!!)..
PS., I used a 5/16" x so long carriage bolt by grinding the square off that's under the head to put my combination together. Just rethread it is all...
I just whacked h-ll outta the top heads using my 3 pound Ford Tool after tightening them together and went!! Work's fine!