diff --git a/libraries/SITL/SITL.cpp b/libraries/SITL/SITL.cpp
index d2fa2547d0..ebc08e201a 100644
--- a/libraries/SITL/SITL.cpp
+++ b/libraries/SITL/SITL.cpp
@@ -47,12 +47,12 @@ const AP_Param::GroupInfo SITL::var_info[] = {
     AP_GROUPINFO("WIND_SPD",   9, SITL,  wind_speed,  0),
     AP_GROUPINFO("WIND_DIR",  10, SITL,  wind_direction,  180),
     AP_GROUPINFO("WIND_TURB", 11, SITL,  wind_turbulance,  0),
-    AP_GROUPINFO("GPS_TYPE",  12, SITL,  gps_type,  SITL::GPS_TYPE_UBLOX),
+    AP_GROUPINFO("GPS_TYPE",  12, SITL,  gps_type[0],  SITL::GPS_TYPE_UBLOX),
     AP_GROUPINFO("GPS_BYTELOSS",  13, SITL,  gps_byteloss,  0),
     AP_GROUPINFO("GPS_NUMSATS",   14, SITL,  gps_numsats,   10),
     AP_GROUPINFO("MAG_ERROR",     15, SITL,  mag_error,  0),
     AP_GROUPINFO("SERVO_SPEED",   16, SITL,  servo_speed,  0.14),
-    AP_GROUPINFO("GPS_GLITCH",    17, SITL,  gps_glitch,  0),
+    AP_GROUPINFO("GPS_GLITCH",    17, SITL,  gps_glitch[0],  0),
     AP_GROUPINFO("GPS_HZ",        18, SITL,  gps_hertz,  5),
     AP_GROUPINFO("BATT_VOLTAGE",  19, SITL,  batt_voltage,  12.6f),
     AP_GROUPINFO("ARSPD_RND",     20, SITL,  arspd_noise,  0.5f),
@@ -89,15 +89,15 @@ const AP_Param::GroupInfo SITL::var_info[] = {
     AP_GROUPINFO("ADSB_TX",       51, SITL,  adsb_tx, 0),
     AP_GROUPINFO("SPEEDUP",       52, SITL,  speedup, -1),
     AP_GROUPINFO("IMU_POS",       53, SITL,  imu_pos_offset, 0),
-    AP_GROUPINFO("GPS_POS",       54, SITL,  gps_pos_offset, 0),
+    AP_GROUPINFO("GPS_POS",       54, SITL,  gps_pos_offset[0], 0),
     AP_GROUPINFO("SONAR_POS",     55, SITL,  rngfnd_pos_offset, 0),
     AP_GROUPINFO("FLOW_POS",      56, SITL,  optflow_pos_offset, 0),
     AP_GROUPINFO("ACC2_BIAS",     57, SITL,  accel2_bias, 0),
     AP_GROUPINFO("GPS_NOISE",     58, SITL,  gps_noise, 0),
-    AP_GROUPINFO("GP2_GLITCH",    59, SITL,  gps2_glitch,  0),
+    AP_GROUPINFO("GP2_GLITCH",    59, SITL,  gps_glitch[1],  0),
     AP_GROUPINFO("ENGINE_FAIL",   60, SITL,  engine_fail,  0),
-    AP_GROUPINFO("GPS2_TYPE",     61, SITL,  gps2_type,  SITL::GPS_TYPE_UBLOX),
-    AP_GROUPINFO("ODOM_ENABLE",   62, SITL,  odom_enable, 0),
+    AP_GROUPINFO("GPS2_TYPE",     61, SITL,  gps_type[1],  SITL::GPS_TYPE_UBLOX),
+    AP_SUBGROUPEXTENSION("",      62, SITL,  var_info3),
     AP_SUBGROUPEXTENSION("",      63, SITL,  var_info2),
     AP_GROUPEND
 };
@@ -213,6 +213,13 @@ const AP_Param::GroupInfo SITL::var_info2[] = {
 
 };
 
+// third table of user settable parameters for SITL. 
+const AP_Param::GroupInfo SITL::var_info3[] = {
+    AP_GROUPINFO("ODOM_ENABLE",   1, SITL,  odom_enable, 0),
+    AP_GROUPINFO("GPS2_POS",      2, SITL,  gps_pos_offset[1], 0),
+    AP_GROUPEND
+};
+    
 
 /* report SITL state via MAVLink */
 void SITL::simstate_send(mavlink_channel_t chan)
diff --git a/libraries/SITL/SITL.h b/libraries/SITL/SITL.h
index 6b6c3bdaf0..fc89d587fc 100644
--- a/libraries/SITL/SITL.h
+++ b/libraries/SITL/SITL.h
@@ -71,6 +71,7 @@ public:
         mag_ofs.set(Vector3f(5, 13, -18));
         AP_Param::setup_object_defaults(this, var_info);
         AP_Param::setup_object_defaults(this, var_info2);
+        AP_Param::setup_object_defaults(this, var_info3);
         if (_singleton != nullptr) {
             AP_HAL::panic("Too many SITL instances");
         }
@@ -116,6 +117,7 @@ public:
     
     static const struct AP_Param::GroupInfo var_info[];
     static const struct AP_Param::GroupInfo var_info2[];
+    static const struct AP_Param::GroupInfo var_info3[];
 
     // noise levels for simulated sensors
     AP_Float baro_noise;  // in metres
@@ -159,12 +161,10 @@ public:
     AP_Int8  gps_disable; // disable simulated GPS
     AP_Int8  gps2_enable; // enable 2nd simulated GPS
     AP_Int8  gps_delay;   // delay in samples
-    AP_Int8  gps_type;    // see enum GPSType
-    AP_Int8  gps2_type;   // see enum GPSType
+    AP_Int8  gps_type[2]; // see enum GPSType
     AP_Float gps_byteloss;// byte loss as a percent
     AP_Int8  gps_numsats; // number of visible satellites
-    AP_Vector3f gps_glitch;  // glitch offsets in lat, lon and altitude
-    AP_Vector3f gps2_glitch; // glitch offsets in lat, lon and altitude for 2nd GPS
+    AP_Vector3f gps_glitch[2];  // glitch offsets in lat, lon and altitude
     AP_Int8  gps_hertz;   // GPS update rate in Hz
     AP_Float batt_voltage; // battery voltage base
     AP_Float accel_fail;  // accelerometer failure value
@@ -229,7 +229,7 @@ public:
 
     // Body frame sensor position offsets
     AP_Vector3f imu_pos_offset;     // XYZ position of the IMU accelerometer relative to the body frame origin (m)
-    AP_Vector3f gps_pos_offset;     // XYZ position of the GPS antenna phase centre relative to the body frame origin (m)
+    AP_Vector3f gps_pos_offset[2];  // XYZ position of the GPS antenna phase centre relative to the body frame origin (m)
     AP_Vector3f rngfnd_pos_offset;  // XYZ position of the range finder zero range datum relative to the body frame origin (m)
     AP_Vector3f optflow_pos_offset; // XYZ position of the optical flow sensor focal point relative to the body frame origin (m)