Hi, my name is***** will require removing the transmission and partially disassembling the unit to replace the reverse clutches. The reverse clutch drum is right at the front of the transmission. I have removed and replaced only the reverse clutches before to save the cost of an overhaul. You can still expect to pay about $1500 to remove and install the transmission and disassemble to replace the reverse clutches.
Let me know if you need anything else.