Yes, even GM gave up on this concept - back in 1988. TSB on the issue of overly sensitive rear brakes
GMC NUMBER: 88-T-151
GROUP: 5 - Brakes
DATE: August, 1988
CORPORATE
NUMBER: 865010R
SUBJECT: REAR BRAKE SENSITIVITY - HEIGHT SENSING VALVE REMOVAL
MODELS: 1984-86 C/K 3500 AND 1987-88 R/V 3500
THIS BULLETIN IS A REVISION OF TRUCK SERVICE BULLETIN 85-B-79, DATED MAY, 1985, UPDATING FOR MODEL YEARS 1984-1988.
1984-1986 C/K 3500 and 1987-1988 R/V 3500 series trucks are equipped with a rear suspension height sensing device that optimizes the brake proportioning valve setting for the load the vehicle is carrying. The height sensing system adjusts the brake balance in vehicles subjected to a range of loading conditions. Occasionally, vehicle modifications by body builders or owners influence the height sensing device. If a vehicle has had rear suspension modifications that affect its trim height or the spring rate, and the driver comments about the brake modulation characteristics of the vehicle, it is recommended that the height sensing system be removed and the brake system be revised as described below:
It goes on to show a procedure that involves a lot of expensive (and currently NLA) brackets and fittings. But it is most often done using off the shelf brake lines/hoses/fittings and usually comes out looking like this:
