Right rear wheel lock up

1996 chevy blazer 4.3 auto 4wd, 198,453km. I guess with this milage I'v got my fingers crossed! Took it to the dealer and they said it is the ABS brake module. The cost will be $2000.00 plus labour. HA HA! I went to the junk yard and bought one for $150. Installed it, blead it at the wheels (got no air ) and test drove it with no ploblems. Four weeks later it started abs pressure releasing on dry roads and the left rear wheel does intermitent lockup making everyone stare at you like you don't know how to drive.I don't believe that there is abs at the wheel sensors on this model and everything else is new, front pads, rear shoes, wheel cylinders, drums and front rotors. Do I live with this wondering if I or my wife and kids will stop every time or go by to the junk yard and try again. Thank sro