Where is the modulator valve located on a 1990 gmc safari Van 4.3L?

The modulator valve on a 1990 GMC Safari Van with a 4.3L engine is typically located on the transmission, specifically on the side of the transmission case. It is connected to the vacuum line and plays a role in controlling transmission shifting. To access it, you may need to look near the rear of the engine bay, close to the transmission linkage. Always refer to a repair manual for precise locations and guidance.