I have 2000 Horizon (same as 1996-1999 model). I have searched for a rear pole light to fit the socket that FW put in. I have not been able to find one. Looks like we need to change the socket as well.
You can buy the socket for the Attwood and install. You will want to solder and shrink-rap the connections for most reliable connection.
_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings