I assume you are talking about the 1873 Cattleman (not 1876 stated in the post body)
The grips are held in place by the backstrap which is connected via three screws. One on the bottom of the grip, connecting the backstrap to the triggerguard and two at the top of the backstrap connecting it to the back of the frame below and on either side of the hammer.
It is very important to use properly fitted screwdriver when removing the three screws so you don't bugger the slots. Regular screwdrivers are taper ground and since the screws are very tight if they haven't been removed already it is likely the screwdriver will slip out and damage the screw head. You need to use a hollow ground screwdriver that completely fills the screw slot and keep it pushed into the slot while you loosen the screws.
Do a Google search for SAA grips, you'll find plenty.
My 2 cents, hope it helps.
3/319th 173 Airborne Bde (Sep) May '66 - May '67
If you're not living on the edge, you're taking up too much space.