I got a set for my 65 Catalina from Part Source a few years ago. As for brake shoes, I got fronts at Part Source but they did not have a listing for rears. I bought those in Florida at AutoZone. If you need a set of E brake cables I probably have used rears and maybe the intermediate. I can check tomorrow.
Check local spring shops I got a rear set for 64 Catalina a few years ago, & there a "bitch" to get upper bolts out if the same as the 64 US cars. Also check out Amazon ????
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Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.
65 and I believe 66 US Pontiac's do not have the upper spring retainer like the 64's do. Basically jack the car up, undo the rear shocks , the rear axle drops down and springs fall out. Magic!!