I got my 11 5/32" x 2 ¾" rear brakes installed today. Everything went smoothly except for Napa's Maxi-Pack brake hardware kit being incomplete. I tracked down the rest of the parts easily enough, though. The drum brake guide from the FAQ section is a lifesaver. If you haven't seen it, take a look here:
http://www.pbase.com/nufsed/drumbrake
Here is the completed assembly.
Notice how much additional surface area comes with the big brakes. My backing plates came off of a late '70's K10. I did the upgrade for only $70 more than it would have cost me to redo my stock rear drums. Early Classic claims a 28% increase in braking power with the new drums.
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