Has it got a long extension tube off the backing plate at almost a 90 degree angle, with a small air chamber on the end of it? If so, you've got "wedge" brakes that can't be converted to maxi brakes. There are no S-cams inside the drums that the maxis need to work right.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!