We have the Roadmaster Reflex Steering Stabilizer with Mounting Brackets for Class A Motor Homes, # RM-RBK6-RSSA. The sturdy steel spring on this stabilizer keeps your Roadmaster Monaco in line by constantly working to maintain its position. Mount it between the steering mechanism and the chassis for a tight connection that will minimize wander and correct oversteering. view full answer...
Unfortunately the 770 is only sold through a specific dealer and TST only made a limited number of them and doesn't even carry it themselves so finding one might be a bit of a challenge.
If you can't find it you can still go with the TST TPMS for RVs # TST-507-RV-6-C you were looking at with the 507 monitor or you can go with a system like the TireMinder Smart TPMS for RVs # TPMS-APP-6 that uses your smartphone as the monitor. view full answer...
The Hopkins Heavy-Duty, Coiled Trailer Connector Adapter - 7-Way to 6-Pole Round - Center Pin 12V Power # HM47083 should be what you are looking for.
I've included a Help Article with additional information on trailer connectors as well should you have additional questions. view full answer...