I have a 93 s10 blazer 4x4. I can't find anywhere what brake booster I have such as jm3, jm4, jm5. But on the booster it has a stamp ST. Does that mean it's a JM3 for sure? Or are there other models of ST in the other models?

Are there any alternatives that I could put on here that require no modification and will be just as effective? There are no local junk yards to me and the best price in a local parts store is $108 for a Cardone reman.

Can these be rebuilt by a typical shadetree mech?

 

you'll find exactly what you need on the "Service Parts Identification Label" in the glove box. (RPO codes) Look for the number "Jxx".... my '93 has JM3 so I would need to get that specific one.
ST=JM3, ZT=JM7, YC=JM5 etc. are all different sizes.

 

All of them stll swap out and one isn't any better than the others.

 

I didn't know what to look for on the product label (I do now, thanks).

But I know there is a stamp ST on the booster itself so I was just wondering if that alone, knowing it says ST, would mean that it's a JM3.

 

HA... that's what I was wondering... I was hoping I could have saved about $30. But I didn't see this post 'till I got back home today. Picked up a reman JM3 ST at Advance Auto for $88 after using a coupon code for $30 off $100 purchase.

 

The one in my blazer stock was the smaller dual diaphram one. When it went out I pulled a larger single diaphram one out of my parts truck. Can't tell a difference and it still stopped the same.


When I swapped to hydroboost there was a hugh difference. Easy job but not something for everybody. I done it cause I could get the parts and one day my blazer will one tone running gear and 35 or 36 (maybe bigger) tires. Also cleared up some room for taller valve covers when I drop in this 350 sitting in my shop.